GROWTH PERFORMANCE, CARCASS CHARACTERISTICS, MEAT QUALITY AND PROFITABILITY OF LOCAL MALAWI GOATS UNDER PEN FATTENING CONDITIONS MSc. (ANIMAL SCIENCE) THESIS FRANK CHILANGA LILONGWE UNIVERSITY OF AGRICULTURE AND NATURAL RESOURCES MARCH 2020 GROWTH PERFORMANCE, CARCASS CHARACTERISTICS, MEAT QUALITY AND PROFITABILITY OF LOCAL MALAWI GOATS UNDER PEN FATTENING CONDITIONS FRANK CHILANGA BSc (Animal Science), Malawi A THESIS SUBMITTED TO THE FACULTY OF AGRICULTURE IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR AN AWARD OF THE DEGREE OF MASTER OF SCIENCE IN ANIMAL SCIENCE LILONGWE UNIVERSITY OF AGRICULTURE AND NATURAL RESOURCES BUNDA COLLEGE MARCH 2020 i DECLARATION I, Frank Chilanga, declare that this thesis is a result of my own original effort and work, and that to the best of my knowledge, the findings have never been previously presented to the Lilongwe University of Agriculture and Natural Resources (LUANAR) or elsewhere for the award of any academic qualification. Where assistance was sought, it has been acknowledged accordingly. Frank Chilanga Signature : ______________________________________ Date : ______________________________________ ii CERTIFICATE OF APPROVAL We, the undersigned, certify that this thesis is a result of the author’s own work, and that to the best of our knowledge, it has not been submitted for any other academic qualification within the Lilongwe University of Agriculture and Natural Resources or elsewhere. The thesis is acceptable in form and content, and that satisfactory knowledge of the field covered by the thesis was demonstrated by the candidate through an oral examination held on _____________________________________________________ Major supervisor : Dr. Fanny C. Chigwa Signature : _____________________________________________ Date : ______________________________________________ Co-Supervisor : Professor Richard K.D. Phoya Signature : _____________________________________________ Date : ______________________________________________ iii DEDICATION “Imagination is stronger than knowledge” (Robert Fulghum). I dedicate this work to my parents (Foreward Chilanga and Towera Kayira). You have always acknowledged the best in me. Thanks for the encouragement and unconditional love. “Picture Me Rolling.” (2 Pac Amaru Shakur). iv ACKNOWLEDGEMENT My very special and sincere gratitude to my supervisors, Dr. F.C. Chigwa and Professor R.K.D. Phoya for their inspiration, guidance, constructive criticism, advice and support during development of this thesis. The Africa RISING project for is greatly appreciated their financial support. I would like to thank Mr. M. Mpinganjira and Mr. C. Mindozo for their assistance during purchase of experimental animals and other research materials. I acknowledge Mr. S. Mtande and the personnel at Small Ruminant Research Unit at Sakhula for their assistance in caring and management of animals aside from their roles in collection of data. I wish to express my appreciation to Dr. G. Chingala and Alfred Ngwira for the technical advice at different phases of the research project. The assistance by Chifundo Gama, Blessings Yona, John Innocent Chirwa, Imran Paseli, Jerome Jumbe, and Mulunji Mtawali in various laboratory works and data collection is very much acknowledged. All the staff at the Department of Animal Science for their help and support during the entire study period are appreciated. I would like to thank my parents, brothers (Blessings and Foreward Jr) and sisters (Temwa and Towera Jr), for their encouragement and constant support throughout my studies. v I am very much grateful to many friends at LUANAR and elsewhere. Millias Mchimwa, Innocent Mhango, Maxwell Chiphwanya, Joel Phiri, McDonald Chabwera,Thokozani Masamba, Hagience Phiri, Joseph Kimangira, Mathews Ndlovu, Stevens Thengo, Gibson Chikafa, Flywell Kawonga, Chancy Mhango, Jennifer Lane, Kondwani Chiumia and all other individuals I could not mention by name, you were friendly and supportive, I will live to cherish the finest moments we have had in academics and beyond. The heavenly Father for the gift of life as well as blessing me with the opportunity, motivation, patience and endurance that was needed to take on this task. vi ABSTRACT A study was conducted to evaluate the effect of feeding different fattening diets based on locally available non-conventional feed resources on growth performance, carcass characteristics, meat quality and profitability of local Malawi goats fattened under pen feeding. Fifty uncastrated local Malawi goat weaners (5 – 6 months old) with initial body weight of 11.55 ± 2.04kg were divided into five groups of 10 animals each and randomly allocated to five treatment categories as follows: S = 60% Rhodes grass (Chloris gayana) hay + 40% soya bean (Glycine max)-based concentrate; SA = 60% Rhodes grass (Chloris gayana) hay + 40% soya bean (Glycine max) and white thorn tree (Acacia polyacantha) leaf meal-based concentrate; B= 60% Rhodes grass hay (Chloris gayana) + 40% baobab (Adansonia digitata) seedcake-based concentrate; BA= 60% Rhodes grass hay (Chloris gayana) + 40% baobab (Adansonia digitata) seedcake and white thorn tree (Acacia polyacantha) leaf meal-based concentrate; and C = grazing only. Animals in S, SA, B and BA were under pen feeding with total confinement for the entire 84 days trial period while those in C were under extensive management. At the end of the feeding trial, goats were slaughtered for evaluation of carcass and meat quality. Pen fed goats on baobab only-based diet had significantly higher daily gains, final weights and total weight gain, and better feed conversion ratio than the rest of the treatments (P < 0.05). Grazing goats had the least daily gains, carcass weight, final weight and total weight gain. Lightness (L*) and yellowness (b*) of the meat was higher in goats under baobab-based pen feeding diets as compared to all other diets. Goat meat from the control diet was darker than that from the rest of diets (lowest L*). Estimated gross margins were high in grazing animals followed by baobab only-based pen feeding diet. However, baobab only-based pen feeding diet had the highest estimated net profit. Current findings indicate that pen feeding of local Malawi goats based on locally available non-conventional feed resources like baobab seedcake improves growth performance, carcass characteristics, meat quality, and profit. vii TABLE OF CONTENTS DECLARATION................................................................................................................ i CERTIFICATE OF APPROVAL ................................................................................... ii DEDICATION.................................................................................................................. iii ACKNOWLEDGEMENT ............................................................................................... iv ABSTRACT ...................................................................................................................... vi LIST OF TABLES .......................................................................................................... xii LIST OF FIGURES .........................................................................................................xv LIST OF ACRONYMS ................................................................................................. xvi CHAPTER ONE ................................................................................................................1 INTRODUCTION..............................................................................................................1 1.1 Background and problem statement............................................................................1 1.2 Justification .................................................................................................................5 1.3 Objectives of the study................................................................................................7 1.3.1 Overall objective ........................................................................................... 7 1.3.2 Specific objectives ......................................................................................... 7 1.4 Hypotheses ...................................................................................................................8 CHAPTER TWO ...............................................................................................................9 LITERATURE REVIEW .................................................................................................9 2.1 Origin of the local Malawi goat breed .........................................................................9 viii 2.2 General overview of goat production in Malawi .......................................................10 2.3 Roles of goats in Malawi ...........................................................................................12 2.4 Demand for goat meat ................................................................................................13 2.5 Production systems ...................................................................................................13 2.6 Impact of goat production on the environment .........................................................14 2.7.1 Options for fattening goats .......................................................................... 15 2.7.2 Finishing goats under intensive fattening conditions .................................. 16 2.8 Growth performance of goats ...................................................................................18 2.9 Carcass characteristics ..............................................................................................20 2.10 Goat Meat quality .....................................................................................................22 2.10.1 Post-mortem pH and temperature decline ................................................. 22 2.10.2 Meat colour ............................................................................................... 23 2.10.3 Water holding capacity .............................................................................. 25 2.10.4 Tenderness ................................................................................................. 27 CHAPTER THREE .........................................................................................................28 MATERIALS AND METHODS ....................................................................................28 3.1 Study location ...........................................................................................................28 3.2 Experimental animals................................................................................................28 3.2.1 Housing management of experimental animals .......................................... 29 3.2.2 Health management of experimental animals ............................................. 29 ix 3.2.3 Experimental diet and design ...................................................................... 29 3.3 Animal feeds and feeding .........................................................................................30 3.3.1 Feedstuff for animals under pen feeding fattening ...................................... 30 3.3.3 Laboratory analysis of feedstuff .................................................................. 32 3.3.4 Feed formulation and feeding plan for animals under intensive fattening .. 34 3.4 Data collection ..........................................................................................................37 3.4.1 Measurement of voluntary feed intake (VFI) .............................................. 37 3.4.2 Growth performance ................................................................................... 38 3.4.3 Slaughter of goats and carcass evaluation ................................................... 38 3.4.4 Meat instrumental quality and laboratory analyses ..................................... 40 3.4.5 Profitability analysis ................................................................................... .42 3.5 Statistical analysis .....................................................................................................45 3.5.1 Laboratory evaluation of feedstuffs and formulated diets............................ 45 3.5.2 Evaluating the effect of pen feeding diets on growth performance, carcass characteristics and meat quality……………………………………….........45 3.5.3 Effect of baobab seedcake and Acacia polyacantha in pen feeding fattening diets on growth performance, carcass characteristics, meat quality parameters and profitability .................................................................... ………………46 3.5.4 Relative growth coefficients ......................................................................... 47 3.5.5 Effect of Production system on growth performance, carcass characteristics, and meat quality……………………………………....................................47 x CHAPTER FOUR ............................................................................................................48 RESULTS AND DISCUSSION ......................................................................................48 4.1 Nutrient composition, gas production, OMD, ME, SCFA and methane production……………………………………………………………………48 4.1.1. Nutrient composition of major feed ingredients and formulated concentrates ...................................................................................................................... 48 4.1.2 Gas production profiles of feed ingredients and formulated concentrates ................................................................................................................ ......53 4.1.3 Estimated organic matter digestibility (OMD), metabolizable energy (ME), methane (CH4) production, and short chain fatty acid (SCFA) for feed ingredients ................................................................................................ …57 4.1.4. Effect of protein source and A. polyacantha inclusion on Gas production at 24h, Organic matter digestibility, metabolizable energy, estimated enteric methane and short chain fatty acid ............................................................... 60 4.1.5. Effect of A. polyacantha inclusion on enteric methane production ............. 64 4.2 Animal performance and carcass characteristics ......................................................65 4.2.1 Effect pen feeding fattening diets on animal performance and carcass characteristics ............................................................................................... 65 4.2.2 Effect of Baobab seedcake and Acacia polyacantha on animal performance and carcass characteristics of local Malawi goats under pen feeding .... …77 4.3 Effect of pen feeding fattening diets on meat quality ..............................................86 xi 4.3.1 Effect of pen feeding fattening diets on temperature and pH changes .......... 86 4.3.2 Effect of pen feeding fattening diets on chilling loss, drip loss, cooking loss, shear force and meat colour of local Malawi goat weaners………………...93 4.3.2 Effect of Baobab seedcake and Acacia polyacantha inclusion on meat quality parameters .................................................................................................... 97 4.4 Profitability analysis ...............................................................................................100 4.4.1 Gross Margin analysis ................................................................................. 103 4.4.2 Net profit margins ....................................................................................... 106 CHAPTER FIVE ...........................................................................................................107 CONCLUSION AND RECOMMENDATION ...........................................................107 5.1 Conclusion .............................................................................................................107 5.2 Recommendations ..................................................................................................109 REFERENCES ...............................................................................................................110 xii LIST OF TABLES Table 2.1 Livestock in Malawi ......................................................................................... 11 Table 2.2 Slaughter and carcass characteristics of three Indian goat breeds ................... 21 Table 3.1 Formulation of pen feeding fattening concentrates and nutrient composition . 35 Table 3.2 Nutrient composition of Total mixed Rations (TMR) (g/Kg DM) .................. 36 Table 3.2 Treatment layout of intensive fattening concentrate diets ............................... 37 Table 4.1 Nutrient composition of feed ingredients and formulated concentrates (g/kg DM)…………………………………………………………………………...52 Table 4.2 Cumulative gas production after 4, 8, 12, 24, 36 and 48 (mL/200 mg substrate)……………………………………………………………………...54 Table 4.3 Correlation (r) between nutrient composition and cumulative gas production at 24 hours……………………………………………………………………….56 Table 4.4 Estimated OMD, ME, Methane and SCFA ...................................................... 58 Table 4.5 Effect of protein source and acacia inclusion on gas production at 24h (GP 24h), Organic matter digestibility (OMD) (%), metabolizable energy (ME) (MJ/kg DM), estimated enteric methane (ml/200mg substrate) and short chain fatty acid (mol). ............................................................................................... 61 Table 4.6 Performance characteristics of local Malawi goats under different pen feeding fattening diets .................................................................................................. 68 Table 4.7 Effect of extensive and intensive production systems on growth performance .. and killing out characteristics 69 Table 4.8 Killing out characteristics of local Malawi goats under different pen feeding fattening diets .................................................................................................. 73 xiii Table 4.9 Non-carcass components (kg) of local Malawi goats under different pen fattening diets ................................................................................................ 74 Table 4.10 Proportions of non-carcass component (%) of local Malawi goats under different pen fattening diets ......................................................................... 75 Table 4.11 Growth coefficients (± SE) of body components of local Malawi goats under different diets. ................................................................................................ 76 Table 4.12 Effect of protein source and inclusion of Acacia polyacantha on performance characteristics of local Malawi goats under pen feeding ......................... 81 Table 4.13 Effect of protein source and inclusion of Acacia polyacantha on killing out characteristics and Non-carcass components of local Malawi goats under pen feeding .......................................................................................... 82 Table 4.14 Effect of protein source and inclusion of Acacia polyacantha on proportions of non-carcass components of local Malawi goats (%) ................................ 84 Table 4.15 The effect of different pen feeding fattening diets on pH and temperature (oC) values of local Malawi goat carcasses ......................................................... 87 Table 4.16 Effect of pen feeding diets on chilling loss, drip loss, cooking loss, WBSF and colour (L*, a*, b*, Chroma, and Hue angle) of Longissimus thoracis ...................................................................................................................... 93 Table 4.17 Effects of production system on meat quality characteristics of local Malawi . goat weaners 94 Table 4.18 Pearson correlations for meat quality traits for the longissimus thoracis of local Malawi goat weaners (pooled data). ................................................... 96 xiv Table 4.19 Effect of protein source and Acacia polyacantha inclusion on meat quality characteristics. .............................................................................................. 99 Table 4.20 Cost and return structure. ............................................................................. 101 Table 4.21 Treatment means for Gross Margin per unit animal .................................... 105 Table 4.22 Effect of protein source and inclusion Acacia polyacantha on per unit gross margins ....................................................................................................... 105 xv LIST OF FIGURES Figure 4.1 Effect of Acacia polyacantha on Methane production. ................................. 64 Figure 4.2 Trends of post-mortem pH for local Malawi goat carcasses under different pen feeding diets. ........................................................................................... 88 Figure 4.3 Trends of post-mortem temperature for local Malawi goat carcasses under different pen feeding diets. ............................................................................ 89 xvi LIST OF ACRONYMS ADF Acid Detergent Fibre ADG Average Daily Gain ANRL Animal Nutrition Research Laboratory AOAC Association of Organic and Analytical Chemists CCW Cold Carcass Weight CDP Commercial Dressing Percentage CP Crude Protein CT Condensed Tannins DDMI Daily Dry Matter Intake DFD Dark Firm and Dry DM Dry Matter DMI Dry Matter Intake EBW Empty Body Weight FAO Food and Agriculture Organization FBW Fasted Body Weight FCR Feed Conversion Ratio GM Gross Margins xvii GP Gas Production HCW Hot Carcass Weight LT Longissimus Thoracis LUANAR Lilongwe University of Agriculture and Natural Resources MCP Mono Calcium Phosphate ME Metabolizable Energy NDF Neutral Detergent Fibre OMD Organic Matter Digestibility PSE Pale Soft Exudative RDP Real Dressing Percentage SCFA Short Chain Fatty Acid SR Small Ruminants SRP Small Ruminant Production TMR Total Mixed Ration VFA Volatile Fatty Acids WBSF Warner Bratzler Shear Force 1 CHAPTER ONE INTRODUCTION 1.1 Background and problem statement Livestock play an integral role in the livelihood of smallholder farmers by providing economic, social and food security. Almost two thirds of rural households in developing countries are partially or fully reliant on livestock for their livelihoods (Pica-Ciamarra et al., 2015). Goat production is an important venture in Malawi as it substantially contributes to household food and income. It plays a significant role in poverty reduction, food security and improved livelihoods. In Malawi, goat production is practiced under mixed crop-livestock production system where most of the animals are kept by farmers who own less than 1 to 1.5 hectares of land (Chikagwa-Malunga &Banda, 2006). Due to small pieces of land, many households are encouraged to keep goats as opposed to cattle and this has led to a tremendous increase in the population of goats (Chikagwa-Malunga & Banda, 2006). Goats are mainly raised for production of meat under extensive systems, grazing native tropical pastures without supplementation. The nutrients supplied from seasonal natural pastures are inadequate for maintenance and growth resulting in poor growth rates and prolonged periods to attain market weight. This type of management system renders goat keeping less economical. In addition, it makes it difficult to cope up with the demand for goat meat which is increasing due to rapid growth of the human population (Mushi, 2009). 2 Providing adequate good-quality feed to livestock to increase and maintain their productivity is among the major constraints to goat production in southern Africa (Gwaze, Chiminyo & Dzama, 2009). In tropical countries the traditional ruminant livestock feeding system mainly depends on the use of native grasses, legumes, and some foliage (Ilori, Salami, Majoka & Okunlola, 2013). Under such systems livestock production is constrained by scarcity and fluctuating quantity and quality of feed throughout the year. During the dry season, forages undergo a sudden reduction in terms of quantity and quality (Ikyume et al., 2018). As a result, animals consume higher quantity of less palatable forage species, which consequently result in loss of body weight (Dumont, Meuret & Prudhon, 1995). The demand for quality meat in sub-Saharan countries is growing due to expanding markets composed of tourism and mining industries as well as increased disposable income of the society (Khamis, 2015; Hozza et al., 2014). Differences in meat quality attributes in small ruminants could be caused by breed, feeding and management practices (Hozza et al., 2014). Meat production is the most important function of goats in the tropics (Devendra, 1991). Meat is an essential food for human consumption. Meat from goats, which are usually reared under extensive management systems with low inputs, remains an important source of nutrients for people in developing countries particularly in the tropics (Shija et al., 2012; Safari et al., 2012; Mushi, Safari, Mtenga, Kifaro, and Elk, 2009; Department of Animal Health and Livestock Development [DAHLD], 2018). As compared to other red meats, goat meat is lean with favourable nutritive characteristics as greater fat quantities are deposited internally in the form of caul and kidney fat and less in subcutaneous and intramuscular fat depots (Merwe, 2015). 3 The low fat and cholesterol content of goat meat is appealing to the modern health conscious consumers (Hanekom, 2010). Livestock production system may affect meat quality (Hanekom, 2010). Combes et al. (2003) mentioned that extensive production systems result in slightly higher collagen content and a slight to no modification in the heat stability of collagen. This could be attributed to the spontaneous exercise associated with the system. The quantity and thermal stability of collagen affects the firmness, toughness and mechanical properties of meat (Lepetit, Grajales & Favier, 2000). Animals in intensive production systems, where movement is restricted, are finished on high energy and protein concentrate based diets with an aim of optimizing growth. Chemical composition and sensory characteristics of meat from animals under such systems is affected by the restricted movement and the nature of diet as this has a bearing on fat deposition in different fat depots (Webb & O’Neill, 2008). Concentrate and roughage use has been identified as a solution to dry season feeding problems. It has been indicated in literature that fodders conserved in form of hay and silage also play an important role in maintaining ruminant productivity during this critical period. Feeding of crop residues and other products like sugar cane tops, bagasse and brewers’ grains has been recommended for ruminant maintenance during critical periods (Food and Agriculture Organization of the United Nations [FAO], 1997). Chisoro, et al. (2018) stated that high competition for consumption of conventional protein sources between human beings and the livestock industry in the last two decades has resulted in an inadequate supply of dietary proteins. On the other hand, high cost of conventional protein concentrates prevents their use in smallholder ruminant production 4 systems in Sub-Saharan Africa (Anele et al., 2011). Therefore, there is a need to exploit non-conventional protein sources. Research on low-cost and locally available indigenous feed resources is very important, especially those which do not attract competition with human beings and ever-expanding intensive livestock production. The use of local indigenous multipurpose tree products and by-products, such as seed cakes and leaf meals is one of such possible alternatives. Utilization of non-conventional feedstuffs especially when it encourages a shift to other ingredients (leaf meals and tree seed cakes) that are not edible to man but readily available will reduce the cost of feed and maximize the returns from goat production. Adansonia digitata (baobab) seed cake is a potential low-cost and locally available protein source for ruminant diets (Ilori et al., 2013). Baobab seeds are tree-borne oil seeds which occur in the natural environments in the tropics and can contain crude protein (CP) up to 360 g/kg dry matter (DM), phosphorus up to 6g/kg DM, calcium levels of 4g/ kg DM, and zinc levels of 26 mg/kg DM (Assogbadjo, Chadare, Kakai, Fandohan & Baidu-Forson, 2012). Therefore, because of appreciable protein and mineral levels, baobab seeds can be used as protein supplements for small ruminants. Another potential non-conventional source of protein for ruminants is white thorn tree (Acacia polyacantha) leaf meal (Cerrillo & Juarez, 2004). White thorn tree has potential for use as a protein supplement for ruminants in smallholder areas in southern Africa (Mlambo & Mapiye, 2015). Due to its high protein and mineral levels, white thorn tree leaves and pods could meet the protein and mineral requirements of ruminant animals (Chingala, 2018). 5 1.2 Justification Intensification of agricultural management and modernization are commonly recommended for traditional, low productive systems in tropical and subtropical countries with the objective of meeting the growing demand for food of animal origin and providing income opportunities to rural smallholder farmers (Dickhoefer, Nagieb, dos Santos Neutzling, Buerkert & Schlecht, 2012). Finishing animals under confinement before sending them to market is one of the intensification tools and a possible solution to speed up growth (Shirima et al., 2014). Under confinement, energy losses due to movement in search of feed and water are reduced. Common protein and energy sources used for feeding animals under intensive conditions are also used for human consumption, this results in a competition for feed resources. Feeding cost under intensive production is very high and it depends on the price of ingredients used which tend to be influenced mainly by supply and demand. Hence, in order to reduce the cost of feeding and competition with human consumption, the use of non-conventional feed resources like baobab seedcake and White thorn tree could be a reliable alternative to replace conventional protein sources like soya bean. Baobab seedcake is a waste product from baobab fruit juice and oil processing but yet with nutritional value capable of supplementing protein to goats especially in the dry season when nutrient value of natural pastures decline. Baobab seeds contain anti-nutritional factors which include tannins, oxalate and trypsin inhibitors, but in levels too low to cause significant adverse effects in animals (Proll, Petzke, Ezeagu & Metges, 1998; Osman, 2004). Extensive use of Acacia polyacantha is limited by the presence of tannins. However, concentrations of condensed tannins less than 20g/kg DM in the diet does not 6 compromise feed intake, digestibility, and nutrient absorption in steers (Orlandi, Kozloski, Alves, Mesquita, & Avila, 2015). In addition, dietary protein can be bound to tannins in the diet, and as a result, post-ruminal digestible bound protein can contribute to metabolizable protein supply (Makkar, 2003). Tannins present in A. polyacantha could also help to reduce environmental pollution through reduction of enteric methane production. Tannins suppress microbial activities in the rumen hence reduced methane production (Bhatta et al., 2009). Therefore, optimal quantities of A. polyacantha in the diet can be utilized for small ruminant feeding. There is need to employ production systems which can increase the quantity of meat produced so that demand is met. Intensification of goat production through finishing of goats under intensive conditions using locally available non-conventional feed resources is one of the options which could be employed by farmers in order to increase the volume of goat meat. Product quality could also be improved under such setups. Several studies have been carried out to characterize carcass and meat quality traits of local Malawi goats under extensive and semi-intensive systems. However, there is limited information related to carcass characteristics, meat quality and economic feasibility of local Malawi goats under intensive systems on fodder based diets. Therefore, this study evaluated growth performance, carcass characteristics, meat quality, and economic feasibility of fattening local Malawi goats under intensive systems on baobab seedcake and Acacia polyacantha based diets. 7 1.3 Objectives of the study 1.3.1 Overall objective The study was done to evaluate the effect of pen feeding local Malawi goats using locally available non-conventional feed resources on growth performance, carcass characteristics, meat quality and enterprise profitability. 1.3.2 Specific objectives The specific objectives of the study were: 1. To evaluate the nutritive potential of baobab seedcake and Acacia polyacantha for goat feeding. 2. To assess the effect of different pen feeding diets on growth performance, carcass characteristics, and meat quality of local Malawi goats. 3. To evaluate the effect of baobab seedcake and Acacia polyacantha in pen feeding diets on growth performance, carcass characteristics, and meat quality of local Malawi goats. 4. To evaluate the effect of different pen fattening diets on profitability of local Malawi goats. 8 1.4 Hypotheses The null hypotheses for the current study were: 1. The nutritive potentials of baobab seedcake and white thorn tree leaves are not high enough for goat feeding. 2. All pen feeding fattening diets have the same effect on growth performance, carcass characteristics, and meat quality of local Malawi goats. 3. The use of baobab seedcake and Acacia polyacantha in pen feeding fattening diets does not affect growth performance, carcass characteristics, and meat quality of local Malawi goats. 4. Pen fattening diets are not profitable. 9 CHAPTER TWO LITERATURE REVIEW 2.1 Origin of the local Malawi goat breed Goats were among the first farm animals to be domesticated and the wide spread of goats all over the world is due to their great adaptability to different environmental conditions and the different nutritional regimes under which they were evolved and subsequently maintained (Kadim et al., 2003). They proved useful to man throughout the ages due to their productivity, small size, and non-competiveness with him for food. Most of the goats in Malawi are local Malawi goats. The local Malawi goats are a subspecies of goats domesticated from the wild goat of South West Asia and Eastern Europe (Banda, Ayoade, Karua, & Kamwanja, 1993). Apparently, they came from Asia and spread southwards from Egypt and Ethiopia down to Uganda, Kenya, the United Republic of Tanzania, Rwanda and Burundi and then to Malawi (Epstein, 1971). As a result, the Malawi goat bears some resemblance to the small East African type (Banda et al., 1993). The Malawi goats have developed through natural selection and adaptation to harsh environments, utilizing limited vegetation in long dry seasons (Banda et al, 1993). The goats have been used for their milk, meat, hair and skins over much of the world. They are also found in all the three agro ecological zones of Malawi; semi-arid low-lying areas of the Lower Shire Valley and the Lakeshores, plateau areas, and high-altitude areas (Banda et al, 1993). Native African breeds are most importantly known for their capacity for good performance under adverse conditions with minimum input resources besides their 10 hardiness and breeding capacity under harsh conditions (Chinchilla-Vargas, Woodward- Greene, Van-Tassell, Wandui-Masiga, & Rothschild, 2018). Despite the fact that they are generally appreciated that they perform relatively well under harsh conditions, rural goat production in Africa faces challenges that include high disease and parasite prevalence, low levels of management, limited forage availability and poor marketing management (Gwaze et al., 2009) that are responsible for poor overall productivity. 2.2 General overview of goat production in Malawi Meat is the most important use of goats in Malawi. During the last few decades, goats have become steadily important in the rural economy. Goats are well adapted to the harsh environment and limited feed and utilize marginal land to produce high quality protein products. The goat population in Malawi was reported to be 8,374,006 in 2018 representing 80.9% of the total ruminant population (DAHLD, 2018). Most of these animals are kept by smallholder farmers who own less than 1 to 1.5 ha of land (Chikagwa-Malunga & Banda, 2006). Smallholder farmers practice crop/livestock mixed farming for survival. Resource-poor farmers tend to keep goats instead of cattle. This has led to a sharp increase in the population of goats from 5,882,106 in 2014 to 8,374,006 in 2018 unlike cattle and sheep which increased from 1,317,447 to 1,655,389 and 269,830 to 317,491, respectively, during the same period (Table 2.1). 11 1Table 2.1 Livestock in Malawi Species 2014 2015 2016 2017 2018 Cattle 1,317,447 1,398,376 1,470,895 1,540,009 1,655,389 Goats 5,882,106 6,545,306 7,348,361 7,672,737 8,374,006 Sheep 269,830 275,537 286,974 302,090 317,491 Pigs 3,128,599 3,645,626 4,206,167 5,051,874 6,388,283 Chickens 68,177,602 78,121,449 86,772,271 99,995,311 124,581,207 Rabbits 1,330,252 1,408,506 1,518,638 1,735,875 2,285,239 G/fowl 1,732,488 1,816,517 1,841,682 2,008,983 2,173,273 Turkey 215,238 225,407 245,492 268,227 295,643 G/pigs 323,011 330,335 364,410 445,126 560,601 Pigeons 3,798,968 4,329,299 4,932,076 5,823,436 6,882,630 Ducks 1,504,155 1,764,117 2,062,608 2,390,304 2,593,630 Source: DAHLD (2018) 12 Goat production in Malawi is usually practiced under extensive system by smallholder farmers and ranks first among ruminants in terms of numbers and utilization (Maganga, Chigwa & Mapemba, 2015) as mentioned above. Goats remain an integral part of smallholder livestock production in Malawi particularly in drought-prone areas where staple food production is limited by unfavourable climatic conditions such as low rainfall. Livestock keeping farmers particularly goat farmers have prolonged food availability throughout the year as compared to non-livestock farmers. This could be attributed to the availability of cash from goat sales that enable them to purchase staple food hence enhancing their resilience in times of challenges arising from shocks related to climate change and variability (Chikagwa-Malunga & Banda, 2006). 2.3 Roles of goats in Malawi Goats have proved to be of utmost importance in Malawi because they are widely kept by rural poor farmers who rely on them for multiple roles (Malata & Banda, 2009). Goat production is an integral part of farming systems in Malawi and can play an important role in poverty alleviation and improved food security in rural households. Goats contribute to the economy, poverty alleviation and food security of rural households in terms of meat, milk, organic fertiliser in form of manure, income, capital storage, savings, an insurance against emergencies and serving cultural purposes (Malata & Banda, 2009; Dereje, 2015; Al-Khaza’leh, 2015). Maganga et al. (2015) regarded goats as a renewable food source and goats are readily slaughtered and sold in Malawi. Itty, Ankers, Zinsstag, Trawally, & Pfister (1997) referred to goats as a living capital reserve and disaster insurance that can be easily liquidated to provide cash when required. 13 2.4 Demand for goat meat Population growth and a transition to meat-rich diets across many countries has increased the global demand for meat, and there is a world tendency for rapid increase in demand for goat meat (Kadim et al., 2003). There are increasing demands for food of animal origin due to human population growth, increasing urbanization, and rising incomes (Safari et al., 2011). Goat meat is consumed widely throughout the world, especially in developing countries. Meat is the most important use of goats in Malawi (Banda et al., 1993). In Malawi, goat meat demand is increasing in urban and rural areas (Maganga et al., 2015), and there is no taboo against its consumption. There is a huge market potential for goat meat as it is becoming an ideal choice for health-conscious consumers (Kadim et al., 2003). Live goats are also on high demand during festive seasons. Potential markets in the Persian Gulf countries, Madagascar and Comoro provide an opportunity for improvement and commercialization of the smallholder production system in Malawi (Melewas, Rwezaula, Kaduma & Bahari, 2004). 2.5 Production systems Small ruminants are kept in a wide range of production systems. Goats represent an important livestock component across all agro-ecological zones in sub-Saharan Africa and exist in all production systems (Lebbie, 2004). They are managed either under extensive, semi intensive or intensive production systems. In Malawi, goat production is predominantly under extensive production systems and is usually practised by smallholder farmers under mixed crop-livestock system, where farmers keep small flocks mainly for home consumption and to generate income when needed (Chikagwa-Malunga 14 & Banda, 2006). Under extensive production systems, livestock farming is mainly subsistence and is characterized by low inputs (Herrera et al., 2011). Small ruminants under extensive production system usually rely on self-growing local grasses where they browse freely without being confined and there is no supplement provision. The levels of production under extensive systems are usually low due to poor nutrition and genotype (Mushi et al., 2009). Animals under intensive production systems are kept under confinement and fed a specifically formulated diet with limited or no physical activity (Merwe, 2015). Intensive production systems are implemented during pasture scarcity and to obtain a desired slaughter weight (Notter, Kelly & McClaugherty, 1991). Intensive production is the fastest growing sector in meat production systems and globally produces approximately 40% of meat (all species) globally (Dickson-Hoyle & Reenberg, 2009). Semi-intensive production systems combine extensive and intensive production systems. Goats can browse but are also supplemented with concentrates and mineral salts to complement browsing (Herrera et al., 2011). 2.6 Impact of goat production on the environment Maintaining the good quality of the environment is one of the factors that drives the sustainability of agricultural production systems. Emissions of greenhouse gases (GHG) are represented mainly by the ruminal fermentation of production animals, waste management, rice cultivation, burning of residues from agriculture and soil management for agricultural production (Monteiro et al., 2018). Greenhouse gas emissions (GGE) from livestock and their impact on climate changes are a major concern worldwide 15 (Brouček, 2015). Livestock production contributes a significant amount of GHG emissions worldwide, generating carbon dioxide (CO2), methane and nitrous oxide (N2O) throughout the production cycle (Gemeda & Hassen, 2018). Large amounts of methane via fermentation of feeds in the rumen are created by ruminants (Brouček, 2015). During this physiological digestive process, hydrogen is released by some microbes during fermentation of forage and is used by methanogenic Archaea (methanogens) to convert carbon dioxide to methane, which is released through eructation, normal respiration and small quantities as flatus (Monteiro et al., 2018). Enteric CH4 production from ruminant animals account for 17 – 37% of global anthropogenic CH4 (Brouček, 2015). Sheep and goats contribute about 6.5% of the world emissions, corresponding to 429 thousand Gg CO2-eq, of which 59% is attributed to sheep and 41% to goats; with 299 thousand Gg CO2-eq derived from meat and 130 thousand Gg CO2-eq derived from milk (Monteiro et al., 2018). Gill et al. (2010) reported that approximately 80% of the anthropogenic CH4 emissions are derived from ruminant production, especially in extensive production systems. Extensive farming system of goats causes higher emissions/kg of milk produced (4.08kg CO2-eq) than the semi-intensive and the intensive system (2.04kg and 1.82kg of CO2-equivelants, respectively) (Sintori & Tzouramani, 2015). 2.7.1 Options for fattening goats There are numerous ways to grow and fatten (finish) goats for market, as goats can be successfully fed a variety of feedstuffs and be marketed at various weights, ages, and body conditions. The choice of the finishing programme will vary by farm and market. Before opting for a way to finish animals, one must consider the profitability of the 16 fattening option. This is principally governed by the price of a kilogram meat produced and the price of feed consumed by the animal. Profitability is also influenced by season, year, management, and genetics (Schoenian, 2013). Producers may also have personal preferences as to how they want to fatten their goats. It has been argued that it is difficult to produce a high-grade goat without some concentrate feeding and/or at least high- quality forage (Schoenian, 2013). Profitability of goat fattening is very dependent on duration of fattening, feed consumption until slaughtering, carcass dressing percentage and composition, as well as revenues collected from selling the products. Considering these aspects plus breed differences is very important for optimization of profit. Priolo, Micol, Agabriel, Prache, & Dransfield (2002) argued that highest daily gains and optimal feed conversion efficiency are achieved with intensive rearing on concentrate-based diets. However, high energy intake does not only lead to high growth rates but also to greater retention of body fat in goats (Hoza, 2014). Duration of fattening depends on feed quality, feed intake, feed conversion efficiency and growth potential of the animals. Goats are late maturing and deposit substantial amounts of fat only at high live weights (Dhanda, Taylor, McCosker & Murray, 1999). Confining of grazing animals for intensive management primarily for optimal growth and high weight gain is necessary for economic preparation of animals for slaughter. 2.7.2 Finishing goats under intensive fattening conditions Finishing of animals under intensive fattening conditions involves removing them from open pastures and introducing them to smaller pens and enclosures in order to reduce the amount of movement and time spent searching for feed (Merwe, 2015). Under this 17 practice, weaner animals are collected, and their market value is improved through intensive feeding and management which enhances meat yield and product quality. Young animals are fed higher concentrate diets which results in higher quality carcasses (Ryan, Unruh, Corrigan, Drouillard & Seyfert, 2007). Finishing animals under intensive conditions reduces the production time of an animal and, thereby allowing carcasses from younger animals to be available for the market earlier (da Cunha Leme, Titto, Titto, Pereira & Neto, 2013). Under intensive finishing, one should ensure that there is enough feeding and drinking space, as well as space for animals to rest and ruminate. Allowance should be made for animals to present normal social behaviour. In addition, an understanding of the animal’s natural behaviour as well as indicators of discomfort, such as freezing, struggling, backing away, attempting to escape and vocalisation can lead to improved management strategies that will benefit animal health and production (Minka, Ayo, Sackey & Adelaiye, 2009). Animals under intensive fattening are prone to metabolic disorders which result in morbidity and mortality and so affect production and profit margins (Smith, 1998). As such, inspection of animals for such incidences is important. Many disorders are associated with feeding high concentrate-based diets. Some examples of the disorders are lactic acidosis, rectal prolapse and the formation of urinary calculi caused by a mineral imbalance in the diet, resulting in the blockage of the urinary tract (Jensen & Swift, 1982). Lactic acidosis, which can be characterized by feed rejection as well as depression and may result in lameness, is a metabolic disorder associated with rapid starch fermentation in the rumen when high concentrate levels are fed (Jensen & Swift, 1982). 18 Bowen et al. (2006) recommended gradual adaptation of the rumen microorganisms from high roughage, low concentrate diets to a high concentrate, low roughage diet in order to prevent lactic acidosis. Other diseases that are commonly found in pen feeding systems include eye disorders, foot rot, pneumonia, enterotoxaemia and coccidiosis (Jensen & Swift, 1982). Under pen-feeding options, the profit margin per individual animal is generally low, therefore the economics of scale are required to make it a competitive enterprise, with profits being shared from a large stock of animals. Important production factors which also influence profitability are fattening period, which is related to growth rate and feed conversion efficiency, and initial weight when then animal is introduced to pen feeding fattening (Duddy, Bell, Shands & Hegarty, 2007). 2.8 Growth performance of goats Ecological factors influence growth and development which are essential biological responses, and it is therefore important to consider the factors affecting their outcome in an ecological framework. Growth is a key characteristic of animals and defined it as any change in body size over time (Naric, Oksuz & Aygun, 2017). Growth is influenced by many factors such as genetics, plane of nutrition, age-related changes and the coordinated effects of synthesis and secretion of hormones and growth factors that determine the cell number and size in organs, skeletal muscle, bone and adipose tissue. Primarily, growth performance of small ruminant depends on the availability of good quality feeds and the feeding regime employed by the farmer. Low growth rate is acknowledged to be the major limiting factor in goat production and the plane of nutrition 19 can markedly improve weight gain though the degree of response varies with breed (Kassahun, 2000). Ayo (2002) reported that the growth rate of goats increased between 19.66 g/day to 25.14 g/day under high and balanced plane of nutrition. Energy and protein are major nutritional factors affecting meat production in goats (Tshabalala, Stroydom, Nebb & Dekock,2003; Zahraddeen, Butswat & Mbap, 2008). Generally, large framed animals grow at a faster rate than animals with small frames, and have higher pre- slaughter live and carcass weights than small framed breeds at a similar age. The post- weaning growth of indigenous Malawi goats was reported to be 40 g/day (Kirk, Cooper & Kamwanja, 1994) whereas the black Bengal at the same age grows at 9 – 23g/day (Sebside, Casey, Niekerk, Tegegne & Coertze,2007). The average daily gains for ad libitum concentrate allowance of Norwegian × Small East African goats (SEA) crossbred goats was 95.7g/day (Safari et al., 2009). However, SEA goats under similar dietary regime grew at 49.5g/day with dressing percentage range between 53 and 57% (Safari et al., 2009). The genetic makeup of the animals also affects growth performance and meat quality. Breed effect on meat quality is associated with differences in muscle distribution, muscle physical and biochemical properties in the carcass (Adam, Atta & Ismail, 2010). A study by Safari et al. (2005) reported that genotype influences growth of animals with local breeds in the tropics having lower growth rates than exotic and crossbreeds. It was further found in the study that the Small East African goats aged between 4 to 12 months in Tanzania had lower daily weight gains (28g/day) than crossbreeds (55g/day). Among other factors, sex of the animal influences growth and development. Comparative growth performance study by Safari et al. (2005) indicated that males of many species grow 20 faster than females. This is due to the presence of high amounts of testosterone, an anabolic hormone, which increases the production of growth hormone and eventually enhances growth in intact male animals. As a result, intact males are heavier and leaner at a given age than castrates and females, whereas castrates tend to be heavier and leaner than females at the same age under similar management systems. However, Birteeb, Danguah & Salifu (2015) indicated that the sex of kids had no significant effect on birth weight, yearling weight and post-weaning growth rate as both male and female kids were very comparable in these traits. The similarity in birth weight in this study may be attributed to the use of genetically superior breeding animals in a planned breeding and selection programme at the breeding station where the study was conducted. This finding agrees with Prpic, Vnucec, Mioc & pavic (2010) who reported no significant difference in birth weight as a result of the sex in Croatian multi-coloured goat kids. In Ethiopia, male and female kids of Abergele goats were statistically similar from birth to one-year- old (Deribe & Taye, 2013). However, Akusu & Ajala (2000) reported differences between male and female kids at birth. The significantly higher pre-weaning growth rate of male over female kids clearly translated into significantly higher weights of males at weaning. 2.9 Carcass characteristics Carcass characteristics of slaughter goats may be affected by a number of genetic and environmental conditions as well as specific herd management decisions. Muscling, not body fat is the most important goat carcass characteristic. Dressing percentage is both a yield and value determining factor and is therefore an important parameter in assessing 21 performance of meat from animal (Massae & Mtenga, 1990). Feeding, breed, sex, slaughter weight, age, gut fill and method of dressing the animal affect dressing percentage (Hango, 2005). Dressing percentage rises with slaughter and length of time on feed. Feed efficiency increases as heavier carcasses are produced. Most goats yield dressing percent of 45-52% range (Tadesse, Urge, Animut & Mekasha, 2016); however, most processors do prefer yearling goats, which show considerable fat deposition around the kidneys and heart. A study by Das & Rajkumar (2010) reported that breed affects the carcass characteristics of goats. Among the three breeds of goats studied (Barbari, Jamunapari and Marwari), Jamunapari had the heaviest carcass weight and dressing percentages (Table 2.2). The study further indicated that weights of cut portions of leg, loin, rack and breast and shank were marginally highest in Jamunapari breed. 2Table 2.2 Slaughter and carcass characteristics of three Indian goat breeds Traits Barbari Marwari Jamunapari Carcass weight (kg) 11.54±.85 10.00±.36 12.21±1.13 Dressing percentage 45.11±1.61a 40.66±1.6b 45.14±1.00a Slaughter weight (kg) 25.57±1.73 24.60±.20 26.84±1.98 Empty body weight (kg) 21.44±1.43 19.86±.38 22.00±1.64 Source: Das and Rajkumar (2010) 22 2.10 Goat Meat quality Meat quality is the eating quality of meat which comprises of palatability, wholesomeness in addition to being free of pathogens and toxins (Casey & Webb, 2010). Variations in meat quality attributes are caused by breed, feeding and management practices (Shija et al., 2013). Some of the important meat quality parameters are post- mortem pH and temperature decline, meat colour, water holding capacity, and meat tenderness. 2.10.1 Post-mortem pH and temperature decline In living animals, muscle pH is normally around 7.0 and post mortem pH decline occurs from 7.0 to 5.6-5.4 due to accumulation of lactic acid produced during anaerobic glycolysis from glycogen. Enzymes initiating glycolysis are inactivated at the iso-electric point of proteins and the ultimate pH is reached. According to Immonen, Ruusunen, Hissa & Puolanne (2000), diet of the animal, ante-mortem stress and temperature decline could affect the ultimate pH of a muscle. Critical factors that influence meat quality are post-mortem glycolysis, ultimate pH and the rate at which it is reached. Slaughter kids have an ultimate pH of about 5.8 which is greater than that of lambs and is also seen to be greater in males than in female animals (Casey and Webb, 2010). According to Warris (2010), acidification process in small ruminants takes approximately 12-24 hours. Nutrition has a direct effect on pH decline as it is a determinant for muscle glycogen levels. Studies conducted by Safari et al. (2009) 23 and Wang et al. (2014) established that there was an increase in the rate of pH decline which stabilized at a pH of 5.6 when goats were supplemented with a grain diet. Extensively reared animals which are associated with a low plane of nutrition have relatively small but enough glycogen reserves to ensure a gradual decline in post-mortem muscle pH resulting in meat with slightly higher pH compared to intensively produced animals (Priolo et al., 2001). Extensively produced animals are more susceptible to pre- slaughter stress because they are not used to confinement or handling. Stressing animals prior to slaughter may lead into pale soft exudate (PSE) and dark firm dry (DFD) meat (Webb & Casey, 2010). Extreme stress shortly before slaughter causes pH to decline rapidly to a low pH causing muscle proteins to denature and lose their water binding capacity leading to PSE meat; whereas with DFD meat, glycogen stores are limited and therefore the muscle pH does not drop as low ensuring that the proteins bind tightly to water molecules (Lawrie & Ledward, 2006). Goats tend to have a high glycolytic potential and therefore seem to have a higher sensitivity to ante mortem stress (Webb & Casey, 2010). 2.10.2 Meat colour The colour of meat has a great importance in the acceptance of meat by consumers at the point of purchase at market. Colour is a physical and sensory perception that is used by a consumer in judging meat quality when purchasing meat, as the consumers are accustomed to certain ideals of what the appearance of fresh meat should be. Various factors contribute to the appearance of fresh meat: concentration and type of myoglobin 24 present, the chemical state of the myoglobin, pH of the meat and the light scattering properties of the cut surface (Lawrie, 1998). One of the primary factors influencing consumer purchase behaviour and acceptance is the appearance of fresh meat (Grunert, 2006). Meat with a bright colour is associated with high quality and freshness and is preferred by consumers unlike meat which is too dark/brown or too pale in colour which is perceived as inferior by the consumer (Viljoen, De Kock & Webb, 2002). There are various methods used to measure meat colour, which include subjective visual appraisal where a sample is compared to a range of pictorial standards as well as more objective instrumental methods (Hunt et al., 1991). For either method it is important that the light source as well as sample thickness and orientation remain constant. Instrumental methods that can be applied to measuring meat colour include reflectance photometers, tristimulus reflectance meters, colour difference meters and reflectance spectrophotometers (Boccard et al., 1981). Reflectance measurements are useful in that they closely relate to what the human eye and brain can detect (Hunt et al., 1991). Reflectance measurements are affected by the muscle structure, the amount of surface moisture, intramuscular fat content and concentration of pigments (Hunt et al., 1991). The readings from the above instruments can be applied to colour difference meters with uniform scales in terms of visual lightness such as the Hunter or more common CIE (Commission International De l’Eclairage) Lab systems (Boccard et al., 1981). The CIE Lab colour space system describes colour according to three coordinates namely lightness L*, redness a*, and yellowness b*. Lightness can be plotted by the function L*= 10 Y1/2 with lower L* values indicating a darker sample with 0 indicating pure black. The redness coordinate can be plotted by the function a* = 17.5 (1.02X-Y)/(Y1/2) to give 25 the degree of redness of the sample if the value is positive; if the sample should present a negative a* value it would mean that green pigments are being detected. The b* coordinate can be plotted by b*=7.0 (Y-0.847Z)/ (Y1/2), with a positive value indicating the degree of yellowness, while a negative value indicates the degree of blueness (Boccard et al., 1981). Other characteristics that may be described by the CIE Lab colour space include the Chroma, which is the degree of colour saturation given by (a*2+b*2)1/2, and the hue which describes the colour group and is the difference in wavelength impulses and can be calculated by the function ATAN (b*/a*) (Hunt et al., 1991). Consumers cannot readily distinguish between fresh lamb and chevon (Lee, Kannan, Eaga, Kouakoa & Gertz, 2008), although Chevon has higher L* values than lamb and therefore appears lighter, it also has lower b* values and so is less yellow (Sheridan, Hoffman & Ferreira,2003; Casey & Webb, 2010). The colour of chevon can be affected by the diet that it receives during the fattening phase. Ryan et al. (2007) found that meat from goats fed grain diets was redder and more yellow than pasture fed goats, while also having greater hue and Chroma values. Chevon has higher lightness and redness than lamb because of lower intramuscular fat (Babiker, El Khider & Shafie, 1990). 2.10.3 Water holding capacity The loss of fluids from meat is important because of its economic implication. Water holding capacity of meat, is the ability of the meat structure to hold/retain water during cutting, storage and heating (Sales, 1996). Water accounts for approximately 75% of the 26 weight of meat, and the ability of muscle to retain moisture is key to many meat-quality parameters held in high regard by the industry and consumers (Huff-Lonergan & Lonergan, 2005). Age and diet fed to the animal before slaughter influence water binding capacity (Schönfeldt, Naude, Bok, Van Heerden, Smit & Boshoff, 1993; Ryan et al., 2007). According to Otto, Roehe, Thoelking & Kalm, (2004), high drip losses result to losses in terms of appearance, texture, nutritional value, and attractiveness, thereby compromising the quality of fresh meat and its processing. Larger drip losses are usually linked to a greater level of protein denaturation, because the water-holding capacity (WHC) of meat is affected by the state of the muscle proteins. A rapid pH decline post- mortem may lead to protein denaturation, with serious consequences for the colour, tenderness, and WHC, generating pale, soft, and exudative (PSE) meat. Drip loss is an undesirable phenomenon that occurs in meat with an ultimate low pH (< 5.0). The iso-electric point of actin and myosin myofibril proteins are approximately 5.5 - 5.4, at this pH the myofibril proteins have a net charge of zero and lose their ability to bind water (Warriss, 2010). When the myofibril protein structures are disrupted by cutting, excessive amounts of fluids exude to the cut surface resulting in an undesirable product (Warriss, 2010). A high drip loss is detrimental to the quality of meat and water exuded contains valuable nutritional components (vitamins, protein, minerals and flavour components) (Hamm, 1961). Meat with a high drip loss has a pale appearance (high L* value) because the meat’s light scattering properties are increased by the excessive amount of moisture on the freshly cut surface (Woelfel, Owens, Hirschler, Martinez- Dawson & Sams, 2002; Warriss, 2010). Meat yield decreases with an increase in drip loss which could have significant economic implications for the farmer and producer. 27 Spoilage bacteria flourish in environments with a high- water activity (Aw) therefore an increase in drip loss of meat will have a negative effect on the shelf life of the product (Hamm, 1961). Consumers reject meat with a high drip loss percentage and perceive the meat as being of a poor quality (Rodger, 2001). 2.10.4 Tenderness Tenderness can be described as the impression formed by the consumer when biting into a piece of meat and the ease at which the teeth can penetrate the meat and break it into fragments, as well as the amount of residue that remains after chewing (Lawrie & Ledward, 2006). The Warner-Bratzler method determines the shearing force using a force deformation curve where the peak force and total amount of energy required are recorded (Honikel, 1998). This can be used as an indicator of tenderness, although it does not take into account other factors that influence the perceived tenderness, but can be used to make correlations relating to tenderness. Tenderness can be affected by the texture of the muscle, or the size of the fibre bundle, as well as the size of the muscle fibre and the amount of connective tissue surrounding it (Lawrie & Ledward, 2006). Chevon is considered to be a tough meat that has a greater shear force than that of mutton or lamb due to the manner in which fat is partitioned in the goat carcass (Casey & Webb, 2010). In general, tenderness drops as the age of the animal from which the piece of meat came from increases, and muscles that do more work tend to be tougher than those that do less work from the animal. Extended cooking times or aging the meat at chill temperatures for a few days may improve goat meat tenderness. 28 CHAPTER THREE MATERIALS AND METHODS 3.1 Study location The study was conducted at Lilongwe University of Agriculture and Natural Resources (LUANAR), Small Ruminant Research Unit at Sakhula, Lilongwe district. The farm lies between latitudes 14.18 o S and longitudes 33.76 o E at an elevation of 1158m above the sea level. The area experiences maximum temperature of 260C-280C and a minimum temperature of 160C to 190C. Average annual rainfall is 900mm. The common forage species in the rangeland were Chloris gayana, Pennisetum purpureum (Napier grass), Paspalum notatum (Bahia grass), Stylosanthes guianensis (Oxyley stylo), and Desmodium intortum (green leaf Desmodium). The trial was conducted between June and September. 3.2 Experimental animals Fifty intact male goat weaners aged from 5 to 6 months (soon after weaning) were used in the feeding trial. The age of the goats was verified with dentition. Animals were purchased from farmers around the experimental site, Bunda College. All the animals were ear-tagged for individual identification, and then subjected to a two week’s adjustment period before being allocated to one of the five treatments. 29 3.2.1 Housing management of experimental animals Experimental goats were kept under roof in individual compartments of a raised pen during the entire feeding trial period. The pen had a raised floor made of timber which was 1-meter-high from the ground. Each individual pen was measuring 1.5m x 1.5m giving around 2.25m2 floor allowance per goat. The roof was covered with corrugated iron sheets. Each compartment had one plastic feed trough and one plastic water trough. Individual goats were given experimental diet and had adlib access to clean water in their specific compartment throughout the entire feeding trial period. 3.2.2 Health management of experimental animals Experimental animals were subcutaneously injected with Ivermectin against external and internal parasites, and drenched with a dewormer (Valbazen) to protect them from gastrointestinal tract parasites. They were also sprayed with an acaricide (Amiltraz) against ticks. Before the onset of the experiment, long acting Oxy tetracycline 20% was intramuscularly administered to all experimental animals based on their body weight to control against Contagious Caprine Pleural Pneumonia (CCPP). 3.2.3 Experimental diet and design After undergoing an adjustment period of two weeks, all the goats were weighed and then randomly allocated to five treatments categories in a completely randomized design. Randomisation was done by picking piece of papers bearing tag numbers from bags 30 without looking and each tag number represented a specific goat. Each of the five treatments had a total of 10 local Malawi goat weaners. The five treatments were as follows; S = 60% Rhodes grass hay + 40% soya bean based concentrate, SA = 60% Rhodes grass hay + 40% soya bean and Acacia polyacantha based concentrate, B = 60% Rhodes grass hay + 40% baobab seedcake based concentrate, BA = 60% Rhodes grass hay + 40% baobab seedcake and Acacia polyacantha based concentrate, and C = rangeland grazing only (control). Animals in S, SA, B, and BA were managed under intensive production systems with total confinement for the entire trial period with Rhodes grass hay and concentrates for their nutrition. Animals in the control category (C)were under extensive management and were herded on natural vegetation around the study area from 0730 hours to 1200 hours in the morning, and then from 1300 hours to 1430 hours in the afternoon. Between 1200 hours to 1300 hours, animals had free access to drinking water. All the fifty experimental animals were given mineral licks. Experimental animals were also subjected to 10 days for adaptation to the experimental diet before the 84-days actual trial phase. 3.3 Animal feeds and feeding 3.3.1 Feedstuff for animals under pen feeding fattening Rhodes grass (Chloris gayana), Acacia polyacantha leaves, soya bean, baobab seedcake (Adansonia digitata), maize bran, salt, monocalcium phosphate and mineral licks were used for feeding animals under pen feeding. Maize bran was the basal energy feed used 31 Acacia polyacantha leaves and Rhodes grass were harvested at Bunda farm. Acacia polyacantha leaves were harvested by cutting branches when the plant had reached its full maturity between the months of May and April. After sun-drying the leaves on a concrete floor for 2 days, they were then collected from the concrete floor after whipping the branches with a stick. Thereafter, resulting leaves were sieved to remove any thorns and twigs before packing them in 50kg bags awaiting trial. Rhodes grass was cut using a sickle, dried in the shade for 4 days and then baled. Rhodes grass hay was chopped to about 5 to 10 cm long using a bush knife and offered as a total mixed ration with the concentrates. A step-up programme for a period of 10 days was used to gradually adapt experimental goats from roughage (Rhodes grass hay) to the concentrate diets. During the first day of the adaptation phase in the feeding trial, 2 goats from treatment 3 died as a result of pneumonia and complexities related to adaptation of the experimental diet. These animals were replaced the following day of the adaptation phase hence the mortalities did not lead to unequal numbers in the treatments later in the actual trial period. Goats were given respective diets ad libitum. Daily allowance for feed was fixed at 1.3 kg of feed (as fed) per head for animals under intensive system. This amount was decided after finding out that there was at least 15% leftover from the daily allowance. Clean drinking water was provided ad libitum. Baobab seedcake which is a by-product from baobab oil processing was bought in 50 kg bags from a local company in Lilongwe City that processes baobab oil and baobab fruit pulp juices. Soya bean, maize bran, salt, mineral licks and monocalcium phosphate were purchased from agricultural and veterinary input shops in Lilongwe. 32 3.3.3 Laboratory analysis of feedstuff 3.3.3.1 Nutrient composition analysis Nutrient composition analysis of feed ingredients and formulated rations was conducted at Animal Research Lab (ARL), LUANAR. All samples were prepared by grinding using a laboratory mill to pass through a 1-millimetre mesh screen, packed in airtight plastic containers, ready for the different analyses. Analysis for dry matter (DM) was determined by oven drying all samples at 105 °C for 5 hours. Ash content was determined by igniting the dry samples in a muffle furnace at 550 °C for 6 hours to burn off all the organic material and the inorganic material which did not get volatilized was recorded as ash. Analyses for crude protein and ether extract were determined using methods described by Association of Organic and Analytical Chemists [AOAC] (2002). Methods of Van Soest, Robertson & Lewis (1991) were used to analyse fibre components of the forage samples, neutral detergent fibre (NDF) and acid detergent fibre (ADF), using the ANKOM200 Fibre Analyser (ANKOM Technology Corp., Fairport, NY). 3.3.3.2 In vitro gas production Feed samples were incubated in vitro with rumen fluid in calibrated glass syringes following the procedure of Menke & Steingass (1988). Rumen liquor was obtained from three fistulated local goats before morning feeding. About 200 mg of 1 mm milled samples were weighed into 100 ml calibrated glass syringes in triplicates. About 30 ml of rumen-buffer mixture was added into each syringe and then all the syringes were incubated in a water bath maintained at 39 oC. The syringes were gently shaken every 33 hour during the first 8 hours of incubation. Readings were recorded after 3, 6, 12, 24, and 48 hours. Feed organic matter digestibility (OMD) (%) and metabolizable energy (ME) (MJkg-1 DM) were estimated from the following Menke & Steingass (1988) and Makkar & Becker (1996) equations based on 24 h gas production (Gv, ml) and crude protein content (CP, %): OMD (%) = 14.88+0.889*Gv +0.45*CP ME (MJkg-1 DM) = 2.20 +0.136*Gv + 0.057*CP Short chain fatty acids (SCFA) was calculated as reported by Akinfemi & Mako (2012). SCFA = 0.0239*Gv – 0.0601 3.3.3.2 Estimation of Methane Gas As described by Fievez, Babayemi & Demeyer (2005), 4 ml of sodium hydroxide (NaOH) (10M) were introduced into the gas syringes, 24 hours post incubation, to estimate methane production. In this procedure, NaOH reacts with carbon dioxide in the gas syringes such that the remaining gas is mostly methane gas. The merit of this method is that it is less costly and reliable in ranking ruminant feed in terms of enteric methane production. 34 3.3.4 Feed formulation and feeding plan for animals under intensive fattening Experimental animals were fed a Total Mixed Ration (TMR) which constituted of 60% roughage and 40% concentrate mixture. Major ingredients for the concentrate portion of the TMR were soya beans, baobab seedcake, Acacia polyacantha leaves and maize bran. After chemical analysis of these ingredients a concentrate ration was formulated. All the concentrate diets were isonitrogenous and basing on the source of protein and inclusion of Acacia polyacantha, concentrate diets were formulated as follows; Concentrate 1= Soya bean only, Concentrate 2= combination of soya bean and Acacia polyacantha, Concentrate 3= baobab seedcake only, and Concentrate 4=combination of baobab seedcake and Acacia polyacantha. Generally, inclusion of Acacia polyacantha reduced the quantity of the major protein source used for formulation of concentrate diets. This could minimize the cost per 100 kg feed formulated. The roughage portion of the ration which was made up of Rhodes grass hay contributed 60% of the Total Mixed Ration. The principal energy source throughout the concentrate diets was maize bran. 35 3Table 3.1 Formulation of pen feeding fattening concentrates and nutrient composition INCLUSION (% as fed) Concentrate 1 Concentrate 2 Concentrate 3 Concentrate 4 Feed Ingredients Maize bran 79.9 77.05 72 69.9 Soya bean 18.1 16.45 0 0 Baobab Seedcake 0 0 26 23.6 Acacia polyacantha 0 4.5 0 4.5 Salt 1 1 1 1 Mono Calcium Phosphate 1 1 1 1 Total 100 100 100 100 Total CP% as calculated 16 16 16 16 Chemical composition (g/kg DM) Dry matter 912.6 911.2 910.4 908.8 Crude protein 160.8 160.5 160.8 160.7 Neutral detergent fibre 291.2 360.4 321.5 336.1 Acid detergent fibre 138.9 170.7 177.1 210 Fat 150.0 132.0 147.2 141.5 Ash 59.6 59.7 64.1 68.5 36 4Table 3.2 Nutrient composition of Total mixed Rations (TMR) (g/Kg DM) TMR 1 TMR 2 TMR 3 TMR 4 Chemical composition Dry matter 901.6 901.0 901.3 900.0 Crude protein 108.8 108.5 108.6 108.7 Neutral detergent fibre 571.4 599.1 582.5 589.4 Acid detergent fibre 380.0 392.7 385.1 408.4 Fat 73.3 66.1 70.4 69.9 Ash 75.6 75.7 75.6 79.2 Principally, the four pen feeding concentrates were formulated in a 2x2 factorial arrangement with protein source and inclusion of Acacia polyacantha as main factors. Baobab seedcake and soya bean meal were the main protein sources used in formulation of the rations whereas factor levels for the second factor were whether Acacia polyacantha was included or not as illustrated in Table 3.2. 37 5Table 3.2 Treatment layout of intensive fattening concentrate diets Inclusion of A. polyacantha Protein source With A. polyacantha Without A. polyacantha Soya bean Meal SBM with AP (D1) SBM without AP (D2) Baobab Seedcake BSC with AP (D3) BSC without AP (D4) AP= Acacia polyacantha; SBM= Soya bean meal; BSC= Baobab seedcake; D1= concentrate diet 1; D2= concentrate diet 2; D3= concentrate diet 3; and D4= concentrate diet 4 3.4 Data collection 3.4.1 Measurement of voluntary feed intake (VFI) During the feeding trial, individual daily dry matter intake (DDMI) was calculated for each goat as the arithmetic difference between the amount offered and amount refused after each meal. Thus, average weekly dry matter intake DMI for a treatment category was calculated from the pooled data and averages were calculated per treatment group. Most of the concentrates were consumed as little or no traces of leftovers were apparently observed. 38 3.4.2 Growth performance Experimental animals were weighed for three consecutive days towards end of 10 days adaptation period. Average weight taken over the three days was recorded as the initial body weight for each treatment group. Thenceforward, live weight was recorded weekly in the morning. Weekly weight gains were used to compute growth rate of the goats. Average daily gain (ADG), DDMI and feed conversion ratio (FCR) were calculated weekly for each individual animal throughout the trial period and averages were calculated for these parameters per treatment group. FCR was calculated as the dry matter intake divided by weight gained per week. Final body weight was recorded at the end of the feeding trial. Average daily gain was calculated as the difference between final live weight and initial live weight divided by the number of days of the feeding trial as below illustrated: ADG (g/day) = (Final weight (kg) – Initial weight (kg) / Number of days) x 1000 FCR= DMI/weight gain 3.4.3 Slaughter of goats and carcass evaluation After the 3 months feeding trial period, the goats were slaughtered and dressed using standard commercial techniques. Ten goats from each treatment were slaughtered and used for carcass evaluation. Slaughtering process was done at Animal Science Department, LUANAR. The day prior to slaughter, animals were fasted overnight. Using a stunning gun, goats were rendered unconscious, exsanguinated and allowed to bleed for 39 5 minutes. No electrical stimulation was done. The animals were hung by both hind legs after slaughter to allow thorough bleeding. The head was removed by further cutting the neck and severing it from the spinal column at the occipito-atlantal articulation. The trotters were removed by severing the joint between the humerus and the scapula (and ulna) in the forelimbs and severing the joint between the femur and the tibia in the hind limbs. The carcasses were then skinned and eviscerated. Appendages (head, skin and feet), the pluck (heart, lungs and trachea) and viscera organs (liver, spleen, kidney, and pancreas were separated and weighed. The pH and temperature of the carcasses were measured 45 minutes after slaughter in the longissimus muscle. Dressed carcasses were weighed within one hour for hot carcass weight and then chilled for 24 hours at 4 degrees Celsius and weighed again for cold carcass weight. The rumen and the intestines were first weighed with contents (fill) and later when emptied. The rumen and the intestine fill were subtracted from the fasted body weight (FBW) to obtain the empty body weight (EBW). Hot carcass weight (HCW) of each goat was recorded after removal of non-carcass components (head, skin, feet, lungs and trachea, liver, heart, spleen, pancreas, gastro-intestinal tract, diaphragm and testicles). Hot carcass included kidneys and perinephric-pelvic fat as described by Colomer-Rocher, Morand-Fehr & Kirton (1987). After 24 hours in cold storage at 4 °C, the chilled carcass weight (CCW) was also recorded. Dressed carcass percentages were calculated using chilled carcass weight (CCW), hot carcass weight (HCW), FBW, and EBW. The commercial and real dressing percentages (CDP and RDP respectively) were calculated as follows: CDP = (CCW/FBW) × 100 40 RDP = (HCW/EBW) × 100 Chilling loss was computed as the difference between hot and cold carcasses weight divided by hot carcass weight expressed as a percentage: Chilling losses (%) = ((HCW-CCW)/HCW) × 100 3.4.4 Meat instrumental quality and laboratory analyses The longissimus thoracis (LT) muscle (6th–13th ribs) was excised (24 hours post- mortem) from the left side of the carcass for various physical meat quality measurements in the laboratory (drip and cooking loss, colour, and instrumental tenderness). All physical measurements were made on fresh muscles excised 24 hours post-mortem. 3.4.4.1 Temperature and pH The pH and temperature of LT muscle were measured on the left side of each carcass. Initially, pH (pH45) and temperature (T45) were measured within 45 minutes post slaughter. Later readings were taken at 3, 6, 12 and 24 h post-mortem whereby the pH measurements were indicated as pH45, pH3, pH6, pH12 and pH24 (ultimate pH), respectively. Temperature measurements were indicated as T45, T3, T6, T12 and T24, respectively. Both pH and temperature were directly measured on the (LT) muscle between the 12th and 13th thoracic vertebrae. The measurements were taken with a Testo 205 handheld portable pH meter with a temperature probe (Model: Knick-portamess, 911, Germany) and calibrated with standard buffers (pH 4.0 and pH 7.0) provided by manufacturer. 41 3.4.4.2 Colour Colour was measured using the CIE colour system, using Konica Minolta CR400 Chroma Meter. Colour measurement samples were prepared as described by Honikel (1998). Meat colour was measured at 24 h on cut surface of 2.5 cm thick samples from the fat-free area. The samples were bloomed (exposed to atmosphere) at 8°C for 30 minutes. Nine meat colour measurements were taken on the bloomed surface at random positions (three measurements for each colorimetric coordinate). Colour coordinate value was determined by calculating the average of the nine measurements. Colour was evaluated using the CIELAB colour space. The three colorimetric coordinates: L* (lightness), a* (redness) and b* (yellowness) were obtained. Sample colour intensity (Chroma) and dimension (hue angle) was also calculated. Chroma (C*) and Hue angle (H*) were calculated with following formulae as described by Wyszecki & Stiles (1982): C*= √ (a*2 + b*2) H* = tan-1 (b*/a*) 3.4.4.3 Drip loss Drip loss (%) of LT muscle was determined using the method described by Honikel (1998). Meat samples were weighed and then suspended from a wire in individually sealed inflated polyethylene bags, without any contact with the bag, inside a refrigerator. After a 24 h storage period at 4 °C in the refrigerator, the samples were gently dried with tissue paper, and reweighed. The total drip loss of each sample was calculated by determining the total weight loss (g) of the sample during storage and expressing it as a percentage (%) of the total weight (g) (Honikel, 1998). 42 3.4.4.4 Cooking loss The total weight loss (g) of a fresh meat sample during cooking was determined by using the method described by Honikel (1998). In order to measure cooking loss (%), a piece of sample taken from LT muscles was weighed (g) and packed into a watertight plastic bag and then placed in a preheated thermostatically controlled water bath set at 80 °C for 1 hour. After the cooking period, the fluids in the bag were drained and the sample was cooled at 4 °C for 2 hours. Thereafter, the sample was blotted dry with tissue paper to remove excess moisture and then weighed for determination of cooking loss (%). The following formula was used to calculate the cooking loss of each sample: Cooking loss (%) = (Cooked Weight/ Fresh Weight) x 100. 3.4.4.5 Warner-Bratzler shear force (objective measurement of tenderness) Cooked meat samples used for measurement of cooking loss were then used to determine shear force value as described by Honikel (1998). Warner Bratzler Shear Force was performed using Stable Micro System Texture analyser (model number TA.XTplus). The Instron machine was set to operate with a load cell of 2.000 KN at a speed of 200 mm /min. The shear force values obtained were then expressed in Newton (N). For statistical analysis, the mean of three readings were used per sample. 3.4.5 Profitability analysis In order to make an economic performance evaluation for treatments, the cost return structure was computed for each treatment. The total investment was computed including 43 the cost of goat housing. Goat housing was calculated based on straight line method of depreciation. Average returns and costs per production system were calculated to provide a platform for calculating gross margins and net profits. The costing assumptions were as follows: goat weaners bought at K10, 000/ animal, soya bean was bought at K250/kg, baobab seedcake was bought at K87.5/kg, K15, 000 for transportation, wage costs during hay making for animals under pen feeding, feeding and water troughs bought at K500 each with an estimated life span of 150 days, housing structures costed at K530, 000 with an estimated life span of 5 years. On salaries, one worker was employed per pen feeding treatment, while two workers were employed to manage animals under grazing. The salary for workers managing animals under pen feeding was 16, 000 per month while workers managing animals under grazing was 13, 000 per month. 3.4.5.1 Gross margin analysis The present study used the gross margin (GM) approach to compare profitability between intensive and extensive production systems but also that of different pen diets. Gross margin is the difference between total gross income and total variable costs. According to Ahmad et al. (2005), gross margin is the most common and accurate estimate of determining profitability. Gross margin provides a simple method for comparing the performance of enterprises that have similar input requirements for capital and labour. Gross margin was computed as the difference between gross revenues and total variable costs as indicated in the equation below. The gross revenues were calculated as a product of the unit price of goat meat and the quantity of production, including the estimated selling prices for all non-carcass components. Total variable costs were calculated as the 44 summation of the product of the unit input cost and the quantity of each input used in production. GM= GI - TVC Where: GM= Gross margin (in Malawi Kwacha (K)) GI= Gross income (Quantity *unit price in K) TVC= Total Variable Costs (K) 3.4.5.2 Net profit The residual income remaining after all operational expenses, including fixed overheads, have been deducted from total revenues is called net profit. According to Mbaso & Kamwana (2013), net profit shows how good an enterprise is at converting revenue into profits attributable to owners. Net profit was determined as indicated in the equation below: NP = GM – FOH Where: NP = Net Profit GM = Gross margin as calculated using Equation A FOH = Fixed Overheads 45 3.5 Statistical analysis The data managed and analysed using R version 3.5.1 (R Core Team, 2018). Analysis of variance (ANOVA) using the General Linear Model and simple regression analysis were used for statistical testing. Significant differences between means were assessed using Tukey Honestly Significance Difference. The relationship between parameters was determined using Pearson correlation coefficients. Relative growth coefficients were estimated using the equation of Huxley (1972). 3.5.1 Laboratory evaluation of feedstuffs and formulated diets ANOVA was performed on chemical composition, in vitro gas production, methane gas production, metabolizable energy and organic matter degradability of formulated diets and major feed ingredients using model I below. The effect of protein source and Acacia polyacantha inclusion on nutritive value parameters of the diets was determined by subjecting the data to two-way ANOVA with interaction as outlined in model II below. 3.5.2 Evaluating the effect of pen feeding diets on growth performance, carcass characteristics and meat quality Effect of treatment group on growth and carcass characteristics was analysed using one- way ANOVA. The following statistical model was applied for evaluation. Yij= μ + Ti + Ԑij…………………………………………………………………………………… (model I) 46 Yi j= Response variable (growth performance, carcass characteristics, meat quality, profitability) μ =Overall mean Ti= Treatment effect (i = 1-5) Ԑij= Random error component 3.5.3 Effect of baobab seedcake and Acacia polyacantha in pen feeding fattening diets on growth performance, carcass characteristics, meat quality parameters and profitability Two-way ANOVA was used to screen the effect of baobab seedcake and inclusion of acacia polyacantha in pen feeding diets on growth performance, carcass characteristics, meat quality and profitability. The following statistical model was used: Yijk = μ + αi(i=1,2) + βj(j=1,2) + (αβ)ij + Ԑijk …………………………………… (model II) Yijk= response variable μ= overall mean αi= effect of protein source (1=soybean and 2= baobab seedcake) βj= effect of acacia polyacantha inclusion (1=included and 2= not included) (αβ)ij= interaction effect of protein source and inclusion of acacia polyacantha Ԑijk= random error term 47 3.5.4 Relative growth coefficients Using empty body weight as independent variables (X), the relative growth coefficients (b) for body and carcass components (Y) were estimated from data pooled for all animals but separately by experimental diet using the equation of Huxley (1972). Relative growth coefficients were compared Tukey Honestly Significant Difference Test. log Y = log a + b log X 3.5.5 Effect of Production system on growth performance, carcass characteristics, and meat quality A simple linear regression model was used to measure the effect of production system on growth performance, carcass characteristics, and meat quality parameters. The simple linear regression model was specified as below: Υ= β0 + β1X1 + Ԑ Y= Growth performance, carcass characteristics, and meat quality parameters β0= constant X1= Management system (0= extensive management system, 1= intensive management system) Ԑ= Random error term 48 CHAPTER FOUR RESULTS AND DISCUSSION 4.1 Nutrient composition, gas production, OMD, ME, SCFA and methane production 4.1.1 Nutrient composition of major feed ingredients and formulated concentrates Nutrient composition results of different feed ingredients and formulated concentrates are presented in Table 4.1. There were significant differences (P <0.05) in the chemical composition among feed ingredients except for DM which did not vary. CP ranged from 74.0 g/kg DM to 397.5 g/kg DM with Soya bean having the highest content. The CP content of Soya bean was significantly higher than that of baobab seedcake (P<0.05). Acacia polyacantha leaf meal had higher CP than maize bran and Rhodes grass hay but less than that of baobab seedcake (P<0.05) (Table 4.1). The CP content of A. polyacantha determined in this study was lower than that reported by Mtengeti & Mhelela (2006) in semi-arid central Tanzania. However, CP content of A. polyacantha obtained in this study was comparable to that obtained by Rubanza, Shem, Bakengesa, Ichinohe & Fujihara (2007) in north-western Tanzania. Furthermore, CP content of A. polyacantha found in this study was higher than that of other Acacia species viz. Acacia shaffneri, Acacia abyssinica and Acacia ampliceps as respectively reported by Cerrillo & Juárez (2004) in Mexico, Weldemariam & Gebremichael (2015) in Ethiopia and Al-Masri (2013) in Syria. 49 The CP content of baobab seedcake meal used in this study was higher than the value of 204 g/kg DM reported in baobab seed meal reported by Oladunjoye, Ojo & Jamiu (2014) and the value of 201.3 g/kg DM reported by Lamayi, Yirankiyuki, Abubakar & Ayim (2014). Apart from Rhodes grass hay, the CP contents of all other feed ingredients were above 110- 130 g/kg DM CP which is the adequate range for growth and maintenance (Mtengeti & Mhelela, 2006). Relatively high contents of CP in Baobab seedcake and Acacia Polyacantha (Table 4.1) support their potential as feedstuffs for goats in arid and semi-arid regions parts of Malawi. Ingredient CP content variations could be explained by specie differences and this can be ascribed to inherent characteristics of each species’ ability to extract and accumulate nutrients from the soil (Dambe, Mogotsi, Odubeng, Kgosikoma, 2015). The CP content in the formulated concentrates was around 160 g/kg DM and significantly similar (P>0.05) as the diets were formulated to be iso-nitrogenous. All the concentrates involved in this experiment contained enough CP to meet the minimum crude protein requirement (8% of DM) for optimal microbial function, beneath which feeds will not provide the required levels of ammonia for optimum rumen microbial activity (Norton, 2003). As such, this is indicative of the fact the formulated concentrates were of high nutritive quality. According to Van Soest (1994), the major determinants of overall forage quality are NDF and ADF. The NDF and ADF content of feed ingredients ranged from 379.9 g/kg DM to 758.2 g/kg DM and 292.3 to 540.7 g/kg DM respectively. The NDF of Rhodes grass hay was significantly higher (P<0.05) than that of the other ingredients except that of A. polyacantha which were similar (P>0.05). In terms of ADF, Rhodes grass hay had 50 significantly higher (P<0.05) ADF than all other ingredients. Moderate content of NDF in baobab seedcake is indicative of comparatively high digestibility. On the contrary, high NDF content in A. polyacantha observed in this study would be suggestive of low digestibility which could have an adverse impact on animal performance. As highlighted by Ikhimioya (2008), the safe upper NDF limit for small ruminants is 60%. At least 25% of fibre, measured as neutral detergent fibre, is recommended by NRC (2001). Significant variations in the chemical composition of formulated concentrates were noted in NDF and ADF content (Table 4.1). NDF and ADF ranged from 291.2 g/kg DM to 336.1 g/kg DM and 138.9 g/Kg DM to 210.0 g/Kg DM, respectively. Concentrate 4 had the highest levels of NDF and ADF (P<0.05). Soya bean-based concentrates (1 and 2) had significantly (P<0.05) lower NDF and as compared to baobab seedcake-based concentrates (3 and 4). Even though concentrates 2 and 3 were not significantly (P> 0.05) different with respect to ADF, soya bean-based concentrates had slightly lower ADF content than baobab seedcake-based concentrates. This could be because baobab seedcake had significantly higher NDF content, and also higher ADF content even though it was not statistically significant, hence, influencing the NDF and ADF composition of the formulated concentrates. Fat content in the feed ingredients ranged from 22.1 g/kg DM to 224.6 g/kg DM with soya bean having the highest fat content and seconded by baobab seedcake. Rhodes grass hay had the least fat content. Fat content in formulated concentrates ranged from 132 to 150 g/kg DM. Ingredient ash content ranged from 37.9 g/kg DM to 88.5 g/kg DM. The highest ash content was observed in A. polyacantha even though it was not significantly different 51 from that of Rhodes grass hay. In the formulated concentrates, ash ranged from 59.6 to 68.5 g/kg. Several other studies also indicated significant differences in the nutrient composition of various feedstuffs for small ruminants (Ikhimioya 2008; Kemboi, Ondiek & Onjoro, 2017). The differences in chemical composition could be due to several factors that can affect chemical composition of feed, such as stage of growth maturity, species or variety, soil types and growth environment (Chumpawadee et al., 2007). 52 6Table 4.1 Nutrient composition of feed ingredients and formulated concentrates (g/kg DM) DM CP NDF ADF FAT ASH Feed ingredients SBM 911.3 397.5d 379.9a 292.3a 224.6d 53.0b BSC 904.4 310.5c 465.4b 298.0a 130.8c 53.8b MB 910.0 110.1a 462.9b 385.6b 68.8b 37.9a AP 898.0 212.3b 692.1c 342.2ab 38.3a 88.5c RGH 894.2 74.0a 758.2c 540.7c 22.1a 86.3c SEM 0.54 0.80 1.22 1.52 0.38 0.21 P-value 0.247 <.000 <.000 <.000 <.000 <.000 Concentrates Concentrate 1 912.6 160.8 291.2a 138.9a 150.0 59.6 Concentrate 2 911.2 160.5 306.4ab 170.7b 132.0 59.7 Concentrate 3 910.4 160.8 321.5bc 177.1b 147.2 64.1 Concentrate 4 908.8 160.7 336.1c 210.0c 141.5 68.5 SEM 0.06 0.03 0.38 0.46 0.84 0.62 P-value 0.054 0.460 0.004 0.002 0.547 0.720 abcd Means with different superscripts within a column are significantly different (P<0.05). SBM = soya bean meal; BSC = baobab seedcake; MB = maize bran; AP = Acacia polyacantha; RGH= Rhodes grass hay; and SEM = standard error of means. 53 4.1.2 Gas production profiles of feed ingredients and formulated concentrates In vitro gas production of feed ingredients and formulated concentrates after 4, 8, 12, 24, 36, and 48 hours are presented in Table 4.2. Gas production (GP) provides a useful basis from which ME, OMD and SCFA could be estimated even though it is a nutritionally wasteful product (Mako, Babayemi & Akinsoyinu, 2011). GP is usually associated with volatile fatty acid production following fermentation of substrate (Kamalak, 2004). 54 7Table 4.2 Cumulative gas production after 4, 8, 12, 24, 36 and 48 (mL/200 mg substrate). 4HRS 8HRS 12HRS 24HRS 36HRS 48HRS Feed ingredients SBM 10.65a 20.88b 33.23c 53.52c 63.97bc 67.85c BSC 16.43b 27.03c 35.48c 51.83c 64.47c 68.52c AP 7.21a 11.64a 16.92a 24.17a 33.94a 41.6a RGH 10.74a 17.43b 24.25b 34.81b 52.28b 57.07b SEM 0.84 1.07 1.54 2.06 2.65 1.91 P-value 0.000 <.000 <.000 <.000 0.000 <.000 Concentrates Concentrate 1 13.81b 25.89b 38.45b 54.98b 64.91b 68.57b Concentrate 2 11.70a 23.37a 33.44a 51.56a 61.18a 62.88a Concentrate 3 15.36c 28.33c 40.74c 58.39c 71.06d 76.21c Concentrate 4 14.86c 25.59b 37.51b 55.85b 67.42c 71.02b SEM 0.68 0.29 0.44 1.25 0.52 0.62 P-value 0.021 <.000 <.000 0.029 <.000 <.000 abcd Means with different superscripts within a column are significantly different (P<0.05). SBM = soya bean meal; BSC = baobab seedcake; MB = maize bran; AP = Acacia polyacantha; RGH= Rhodes grass hay; and SEM = standard error of means. 55 There was considerable variation in terms of gas production among both feed ingredients and formulated concentrates throughout the incubation periods. Cumulative gas production was significantly different (P<0.05) in both feed ingredients and formulated concentrates at 4, 8, 12, 24, 36 and 48 hours. With respect to feed ingredients, higher gas production was recorded in baobab seedcake and soya bean which had significantly similar gas volumes. Intermediate gas production was observed in Rhodes grass hay, whereas the least gas recordings were recorded in A. polyacantha. Relatively low gas production in Acacia polyacantha and Rhodes grass hay might be due to higher NDF content in the feedstuffs which as stated by Akinfemi & Mako (2012) could result into reduction of microbial activity during the incubation process. The presence of tannins has been reported in A. polyacantha (Chingala, 2018; Rubanza et al, 2003). Least gas productions in Acacia polyacantha in this study could further be attributed to the presence of phenolic compounds which adversely affect microbial activity (Ulger, Kamalak, Kurt, Kaya & Guven, 2017). Considering cumulative gas production (GP) in formulated concentrates at 48h, in an ascending order was Concentrate 20.05). At 24 h, highest cumulative gas production was obtained from baobab seedcake-based diet without A. Polyacantha inclusion (concentrate 3). Again, the highest OMD was obtained from the same combination (P<0.05). According to Al-Masri (2013), OMD is reflected by gas production and more gas production entail more degradation of organic matter. Gas production indicates the degree of fermentation activity. Generally, baobab seedcake-based diets had significantly higher cumulative gas production at 24h compared soya bean-based diets. Inclusion of A. polyacantha in the diets significantly reduced GP 24 h of both Soya bean based and baobab seedcake-based diets (P<0.05). In baobab seedcake-based diets, inclusion of 4.5% A. polyacantha significantly reduced OMD. Even though the reduction was not statistically significant in soya bean-based diets, inclusion of A. polyacantha also reduced OMD in soya bean-based diets. A. polyacantha leaves contain condensed tannins (20 – 22.9g/Kg DM) which in the diet can bind dietary protein and reduce its degradation in the rumen (Chingala, 2018). The same binding mechanism could also reduce cumulative gas production since the activity of microorganisms involved in fermentation is reduced. As such, decreased gas production and OMD after inclusion of A. polyacantha could be explained by the presence of tannins in the feedstuff. Ulger et al. (2017) mentioned that the effect of CTs on the digestibility of nutrients and performance in an animal depends on the amount and biological activity of the condensed tannins. While low levels of CTs have incontrovertible effects on nutrient digestibility and animal 63 performance, high levels of CTs (5% of DM) decrease protein utilization due to excessive formation of tannin-protein complexes (Ulger et al., 2017). Therefore, care must be taken when the leaves of A. polyacantha are incorporated in ruminant diets because they contain tannins. ME differed significantly (P<0.05) with higher values obtained in baobab seedcake-based diets. Methane and SCFA also differed significantly with protein source and inclusion of A. polyacantha (P<0.05). The present study also observed that methane production was generally higher (P<0.05) in soya bean-based diets as compared to baobab seedcake- based diets. On the other hand, SCFA were significantly higher in baobab seedcake-based diets as compared to soya bean-based diets and thus an added advantage as this is an indication that energy is present in the diets. It was also observed that methane production, ME and SCFA were reduced with inclusion of A. polyacantha(P<0.05). This could be attributed to the presence of tannins (phenolic compounds) which suppress the activity of methanogens in the rumen. Cell wall contents (NDF and ADF) and condensed tannin contents are very important factors affecting the nutritive value of feedstuffs. These differ with the phenological stage of plants and increase at the expense of fermentable fractions with increasing maturity. As such, gas production, organic matter digestibility and metabolizable energy values decrease with increasing maturity which tends to increase the condensed tannin and cell wall contents in plants (Kamalak et al., 2011). According to Ulger et al. (2017), condensed tannin and cell wall contents negatively correlate with nutritive value parameters of feedstuffs such as digestibility and metabolizable energy. 64 4.1.5. Effect of A. polyacantha inclusion on enteric methane production The effect of A. polyacantha inclusion on enteric methane production is further illustrated using Figure 4.1. The study indicated that inclusion of 4.5% A. polyacantha in the diets significantly reduced methane production in vitro (P<0.05). From the present in vitro study, inclusion of A. polyacantha in soya bean-based diets reduced methane production by 37.17 %. On the other hand, incorporation of A. polyacantha in baobab seedcake- based diets reduced methane production by around 43.16%. 1Figure 4.1 Effect of Acacia polyacantha inclusion on Methane production. 0 2 4 6 8 10 12 Baobab Soybean E st im at ed e n te ri c m et h an e (m l/ 2 0 0 m g ) with A. Polyacantha without A. Polyacantha 65 4.2 Animal performance and carcass characteristics 4.2.1 Effect pen feeding fattening diets on animal performance and carcass characteristics The effect of soya bean-based, soya bean + Acacia polyacantha-based, baobab seedcake- based, baobab + Acacia polyacantha-based and the control pen fattening diets was investigated on animal performance and carcass characteristics. However, feed conversion ratio and daily DM intake was not estimated for the control diet as it was not easy to capture feed intake data for animals on free range (extensive) management. 4.2.1.1 Effect of pen feeding fattening diets on feed intake There were no significant differences in daily DM intake among intensively managed local Malawi goat weaners which were offered different pen feeding fattening diets formulated from baobab seedcake or soya bean meal with Acacia polyacantha either included on not. Therefore, it can be concluded that the physical and chemical characteristics of the pen fattening diets did not influence daily DM intake in the present study. Dry matter intake regulation in ruminants is governed by long term and short term mechanism. In long term mechanisms, feed intake is adjusted according to the nutrient requirements, while in the short term mechanisms the intake is influenced by short term effects, experienced during periods of ingestion and rumination, which are influenced by gut fill, passage rate and chemical feedback from the rumen (Dulphy & Demarquilly, 66 1994). It can be suggested from the results that the pen fattening diets did not have a significant effect on the short term mechanism for governing feed intake in ruminants. 4.2.1.2 Effect of pen feeding fattening diets on growth performance Means of initial weight, final weight, average daily gain, total live weight gain and FCR are presented in Table 4.6. Pen feeding fattening diets had an effect (P<0.05) on growth performance (Table 4.6). Final weights were significantly different (P<0.05) among the diets and ranged from 14.83 to 18.18kg. The control diet had the least final weight (P<0.05) and average daily gain as compared to all other treatments. Animals managed under pen feeding fattening conditions had higher(P<0.05) final weights and ADG than the control which was extensively managed. Animals on baobab seedcake only-based diet had significantly (P<0.05) superior final weight and ADG. Regression results in Table 4.7 indicate that the average final weight of intensively managed animals was 1.82kg higher than extensively managed animals, average growth rate was 23.00g/day higher than extensive animals, and average total weight gain and Specific growth rate were respectively 1.93kg and 0.13 higher than extensively managed animals. According to Safari et al. (2009), Mushi et al. (2009) and Asizua (2010), concentrate feeding increases ADG due to increased nutrient intake. Furthermore, a study conducted by Claasen (2008) on the effect pen feeding and free-range production systems on the growth rate and carcass characteristics of Dorper lambs under South African conditions concluded that animals managed under pen feeding fattening conditions had significantly higher growth rates and produced significantly higher carcass weights and dressing percentages. Higher final weights and ADG in animals under pen feeding fattening in the present study could be attributed to high energy and protein intakes. Under pen feeding fattening, feed 67 conversion ratio ranged from 9.43 to 14.18 with baobab-based diet having the highest FCR (P <0.001). Superior FCR values in baobab-based diets explain the consequent high ADG and final weight in this treatment. 68 11Table 4.6 Performance characteristics of local Malawi goats under different pen feeding fattening diets Parameter S SA B BA C SEM P-Value Initial weight (kg) 11.58 11.52 11.59 11.58 11.55 0.83 1.00 Final weight (kg) 17.08b 15.56a 18.18c 16.19b 14.83a 0.91 0.006 ADG (g/day) 67.62c 52.02b 78.45d 54.88b 40.24a 4.75 <.000 DDMI (kg) 0.74 0.69 0.73 0.75 - 0.03 0.232 Total live weight gain (kg) 5.68c 4.37b 6.59d 4.61b 3.38a 0.40 <.000 FCR (kg DMI/ kg Wt. gain) 11.12b 13.56c 9.43a 14.18c - 0.95 <.000 abcd Means with different superscripts in the same row differ significantly (P<0.05); SEM= Standard error of mean; S = 60% Rhodes grass hay + 40% Soya bean meal based concentrate; SA = 60% Rhodes grass hay + 40% Soya bean meal and Acacia polyacantha leaf meal based concentrate; B = 60% Rhodes grass hay + 40% Baobab seedcake based concentrate; BA = 60% Rhodes grass hay + 40% Baobab seedcake and Acacia polyacantha leaf meal based concentrate; C = Grazing only; ADG= Average daily gain; FCR= Feed conversion ratio 69 12Table 4.7 Effect of extensive and intensive production systems on growth performance and killing out characteristics Response variable Coefficient Standard Error P-value performance GR 23.006 4.983 <.000 Final weight 1.8225 0.7655 0.021 Total Wt. gain 1.9325 0.4186 <.000 Killing out characteristics Slaughter weight 1.9474 0.7226 0.010 EBW 1.9474 0.6086 0.040 HCW 0.752 0.366 0.045 CCW 0.7434 0.3598 0.044 CDP -0.5183 0.7927 0.516 RDP 0.5331 0.8542 0.536 Reference category= extensive production system; GR= Growth rate; SGR= Specific growth rate; EBW= Empty body weight; HCW= Hot carcass weight; CCW= Cold carcass weight; CDP= Commercial dressing percentage; RDP= Real dressing percentage. 4.2.1.4 Killing out characteristics Table 4.8below indicates the slaughter characteristics of local Malawi goats used in the study. Animals fattened under grazing conditions (control) had the least slaughter weight, empty body weight (EBW), hot carcass weight (HCW), and cold carcass weight (CCW) (P <0.05). Animals on baobab-based pen feeding fattening diet had the highest slaughter 70 weight than their intensively managed counterparts. Similar pattern holds for EBW, HCW and CCW. It is clear in Table 4.8 that goats under extensive production system (control) were significantly smaller goats (slaughter weight) and produced lighter carcasses (hot and cold carcasses) than intensively managed goats. Regression analysis results in Table (4.7) above indicate that animals under intensive management produced animals with significantly higher (P<0.05) slaughter weight, empty body weight (EBW), hot carcass weight (HCW), and cold carcass weight than animals produced under extensive management by 1.95, 1.28, 0.75, and 0.74kg respectively. These results are consistent with the findings of Crouse, Busboom, Field & Ferrell (1981) who noted that pen feeding fattening system produces larger and heavier lambs (live slaughter weight) compared to forage-based diets (free range). There were no significant differences on commercial and real dressing percentages among the fattening diets (Table 4.8). Contrary to the present study, a study conducted by Hanekom (2010) found that intensively produced small ruminants had higher dressing percentages (DP) compared to extensively produced lambs. Similarly, results like these were obtained by different authors (Williams et al., 1983 – cattle; Notter et al., 1991 – lambs; Moron-Fuenmayor and Clavero, 1999 – lambs; Murphy et al., 1994 – lambs). According to Borton, Loerch, McClure & Wulf (2005), lower dressing percentages in extensively fattened animals can be ascribed to thin subcutaneous fat layer together with a well-developed digestive tract. Real dressing percentage of local Malawi goats slaughtered at around 9 months (based on empty body weight) ranged from 52.30% to 54.44%. This was consistent with the range 71 reported by Toplu, Goksoy & Nazligul (2013) for Turkish indigenous hair goat kids reared under an extensive production system. The results of the present study were also consistent with the range of 51.14%reported by Koyuncu, Duru, Kara, Ozis & Tuncel (2007) for Hair goats in semi-intensive conditions and slaughtered at 21 kg live weight and 48-50% reported by Yilmaz et al. (2009) for Hair goat kids, Saanen × Hair goat F1 and Saanen × Hair goat B1 kids slaughtered approximately at 4 months of age under intensive management conditions. Commercial dressing percentage was in the range of 41.14% to 43.72% in the current study. Present study results were consistent with ranges reported by Toplu et al. (2013) for Turkish indigenous hair goat kids (40 to 53%); Marichal, Castro, Capote, Zamorano & Arguello (2003) for Canary Caprine Group genotype kids slaughtered at 6, 10, 25 kg body weight (41 to 53%) and Özcan, Yilmaz, Ekiz, Tölü & Savas (2010) for Gokceada, Maltese and Turkish Saanen kids slaughtered at 11-16 kg body weight (43-52%). The similarities in dressing percentage might mean that the combination effect of subcutaneous fat layer and digestive tract on dressing percentage was not significant enough to influence the dressing percentages of fattened goat weaners at the point they were slaughtered. 4.2.1.5 Effect of pen feeding diets on non-carcass components Mean weights of non-carcass components are presented in Table 4.9. Pen feeding fattening diets had no significant treatment effect on the weight of the head, feet, skin, spleen, liver, lungs, and blood. On the other hand, pen feeding fattening diets had significant treatment influence on weight of empty gut, heart, and digestive contents. The control diet had the least empty gut weight (P<0.001) and digestive contents (P<0.05). Overall, the control diet also produced animals with slightly lighter heart weights than 72 animals under pen feeding. These variations could be attributed to lower visceral fat in extensively managed animals. Intensively managed animals had higher digestive contents (P= 0.001) compared to the control (extensively managed animals). This could be a result of adequate feed under intensive fattening hence higher feed intake in intensively managed animals. 73 13Table 4.8 Killing out characteristics of local Malawi goats under different pen feeding fattening diets Parameter S SA B BA C SEM P-Value Slaughter weight 16.2b 14.55a 17.14c 15.30ab 13.85a 0.85 0.003 EBW 13.02b 12.13b 14.15c 12.73b 11.73a 0.73 0.020 HCW 6.82b 6.43b 7.55c 6.94b 6.18a 0.45 0.041 CCW 6.61b 6.21b 7.27c 6.71b 5.96a 0.44 0.049 CDP 41.14 42.55 42.41 43.72 42.98 0.96 0.123 RDP 52.30 52.95 53.22 54.44 52.69 1.07 0.342 abc Means with different superscripts in the same row differ significantly (P<0.05); SEM= Standard error of mean; S = 60% Rhodes grass hay + 40% Soya bean meal based concentrate; SA= 60% Rhodes grass hay + 40% Soya bean meal and Acacia polyacantha leaf meal based concentrate; B = 60% Rhodes grass hay + 40% Baobab seedcake based concentrate; BA= 60% Rhodes grass hay + 40% Baobab seedcake and Acacia polyacantha leaf meal based concentrate; C= Grazing only; EBW= Empty body weight; HCW= Hot carcass weight; CCW= Cold carcass weight; CDP= Commercial dressing percentage; RDP= Real dressing percentage 74 14Table 4.9 Non-carcass components (kg) of local Malawi goats under different pen fattening diets Parameter S SA B BA C SEM P-Value Head 1.21 1.08 1.20 1.11 1.16 0.08 0.405 Feet 0.46 0.40 0.46 0.41 0.43 0.03 0.241 Skin 0.92 0.86 1.04 0.89 0.87 0.07 0.135 Empty gut 1.75c 1.72c 2.00d 1.59b 1.19a 0.11 <.000 Heart 0.10b 0.10b 0.11c 0.08a 0.08a 0.01 0.005 Spleen 0.02 0.03 0.03 0.02 0.04 0.01 0.357 Liver 0.27 0.27 0.31 0.25 0.26 0.03 0.329 Lungs 0.23 0.21 0.19 0.21 0.19 0.02 0.209 Blood 0.39 0.43 0.47 0.41 0.39 0.04 0.342 Digestive contents 3.18d 2.43b 2.98c 2.57b 2.12a 0.20 0.001 abc Means with different superscripts in the same row differ significantly (P<0.05); SEM= Standard error of mean; S= 60% Rhodes grass hay + 40% Soya bean meal based concentrate; SA = 60% Rhodes grass hay + 40% Soya bean meal and Acacia polyacantha leaf meal based concentrate; B = 60% Rhodes grass hay + 40% Baobab seedcake based concentrate; BA= 60% Rhodes grass hay + 40% Baobab seedcake and Acacia polyacantha leaf meal based concentrate; C = Grazing only 75 15Table 4.10 Proportions of non-carcass component (%) of local Malawi goats under different pen fattening diets Parameter S SA B BA C SEM P-Value Hot carcass* 52.3 52.95 53.22 54.44 52.69 1.07 0.342 Head* 9.26ab 8.93ab 8.49a 8.75ab 9.84b 0.43 0.031 feet* 3.57bc 3.30ab 3.22ab 3.20a 3.67c 0.18 0.037 skin* 7.08 7.08 7.31 7.08 7.49 0.49 0.885 Empty gut* 13.46b 14.30b 14.18b 12.53b 10.10a 0.68 <.000 Heart* 0.76 0.81 0.77 0.67 0.67 0.06 0.111 Spleen* 0.18 0.18 0.20 0.18 0.38 0.10 0.234 liver* 2.07 2.20 2.18 2.01 2.24 0.17 0.657 lungs* 1.73ab 1.79b 1.34a 1.70ab 1.61ab 0.15 0.032 Blood* 2.99 3.51 3.27 3.21 3.32 0.26 0.374 Digestive contents** 19.75c 16.82b 16.87b 16.88b 15.08a 1.48 0.049 *based on empty body weight, ** based on fasted body weight abc Means with different superscripts in the same row differ significantly (P<0.05); SEM= Standard error of mean S = 60% Rhodes grass hay + 40% Soya bean meal based concentrate; SA = 60% Rhodes grass hay + 40% Soya bean meal and Acacia polyacantha leaf meal based concentrate; B = 60% Rhodes grass hay + 40% Baobab seedcake based concentrate; BA = 60% Rhodes grass hay + 40% Baobab seedcake and Acacia polyacantha leaf meal based concentrate; C = Grazing only 76 16Table 4.11 Growth coefficients (± SE) of body components of local Malawi goats under different diets. Relative growth coefficient Parameter Pooled data S SA B BA C Hot carcass 1.09±0.04 1.1±0.13 1.08±0.12 1.25±0.07 1.08±0.06 1.11±0.23 Head 0.75±0.1 0.98±0.17 0.74±0.15 0.82±0.38 0.71±0.13 1.04±0.63 Feet 0.88±0.12 0.74±0.35 1.08±0.19 0.73±0.30 0.93±0.17 1.37±0.64 Skin 0.82±0.15 0.70±0.31 0.99±0.31 1.33±0.43 0.58±0.44 0.25±0.58 Empty gut 1.11±0.18 0.77±0.17 0.60±0.19 0.24±0.15 0.99±0.22 1.28±0.90 Heart 0.74±0.20 0.92±0.36 0.69±0.33 -0.84±0.65 0.53±0.41 0.88±0.90 Spleen 0.72±0.40 0.76±0.40 1.95±0.58 1.75±0.58 0.85±0.46 -0.23±2.81 Liver 0.95±0.18 1.23±0.32 0.95±0.45 -0.13±0.44 0.72±0.40 2.36±0.82 Lungs 0.41±0.23 1.23±0.56 -0.02±0.21 1.26±0.88 0.37±0.28 0.82±1.27 S = 60% Rhodes grass hay + 40% Soya bean meal based concentrate; SA = 60% Rhodes grass hay + 40% Soya bean meal and Acacia polyacantha leaf meal based concentrate; B = 60% Rhodes grass hay + 40% Baobab seedcake based concentrate; BA = 60% Rhodes grass hay + 40% Baobab seedcake and Acacia polyacantha leaf meal based concentrate; C = Grazing only 77 The proportion of various visceral organs reported in the present study (Table 4.10) were similar to those reported by Kadim et al.(2004) in Oman goat breeds, and Tanganyika, Mtimuni, Mfitilodze & Phoya (20014) in indigenous Malawi goats. The proportion of non-carcass parts, such as feet and head, which correlate with poor body growth, were greater in the control diet (extensively fed goats) and these results were consistent with results reported by Karaca (2016) and Moron-Fuenmayor & Clavero (1999). Allometric growth coefficients (Table 4.11) also indicated that the rate of head and feet growth for goats in under extensive management was higher than that of empty body weight. With reference to pooled data (Table 4.11), allometric growth coefficients for the carcasses and non-carcass components were hypoallometric, except for hot carcass and empty gut which were hyperallometric. Even though the liver was less than one, it was closer to achieving isoallometry. The rate of increase of the carcass was higher than that of empty body weight and most offal, except for the empty gut which was slightly above that of the carcass. Basing on pen feeding fattening diets, carcass weight of goats under baobab-based diet increased rapidly compared to the rest of the diets. 4.2.2 Effect of Baobab seedcake and Acacia polyacantha on animal performance and carcass characteristics of local Malawi goats under pen feeding 4.2.2.1 Effects of baobab seedcake and A. polyacantha on growth performance The principal determinant of fattening enterprises is rapid rate of gain. ADG for intensively fattened goats in this study ranged from 52.02 to 78.45g/day (Table 4.14). This level of growth rate was achieved with feed conversion ratios ranging from 9.43 to 78 14.18g of feed/ g gain. This level of performance was higher than that reported by Khamis (2015) for intensively fattened local goats in Tanzania whose ADG ranged from 25-49g/day with FCR ranging from 8 to 16 g of feed/ g gain. On the other hand, results from the present study are comparable to what Mahgoub, Kadim, Al-Saqry & Al-Busaidi (2005) reported for Omani Jebel Akhdar goat for meat production under intensive fattening conditions. From the current study, protein source and inclusion of Acacia polyacantha had no effect on dry matter intake. Protein source significantly influenced ADG (P<0.001) (Table 4.12). Goats fed baobab seedcake-based concentrates under pen feeding fattening conditions had higher ADG and total live weight gains than those on soya bean meal- based concentrate diets. The ADG and total live weight gain was also higher (P= 6.22E- 08) for the diets without Acacia polyacantha. Inclusion of Acacia polyacantha in this study tended to reduce average daily gain. This might symbolize intolerable levels of anti-nutritional factors in the concentrate diets where Acacia polyacantha was included (Ulger et al., 2017). The current study further assumes that low performance in diets where Acacia polyacantha was included could be a result of a synergetic effect of anti- nutritional coming from both the protein sources and Acacia polyacantha meal. Ulger et al. (2017) reported that high levels of condensed tannins reduce nutrient digestibility and animal performance. In the present study, superior FCR was observed in baobab seedcake diets without Acacia polyacantha. Inclusion of acacia polyacantha detrimentally affected FCR. A combination of baobab seedcake and Acacia polyacantha had the most inferior FCR. This can be attributed to high levels of anti-nutritional factors in the diets. Acacia polyacantha contains tannins (Chingala, 2018). Anti-nutritional factors such as oxalate, 79 phytate, saponins and tannins that have also been reported to be present in baobab seed meal (Nkafamiya, Osemeahon, Dahiru & Umaru, 2007) even though at nontoxic level to most livestock animals. The poor feed conversions could be explained by the presence of anti-nutritional factors as earlier mentioned. 4.2.2.2 Effects of baobab seedcake and A. polyacantha in pen feeding diets on killing out characteristics and non-carcass components At the beginning of the experiment, all goats under pen feeding fattening had comparable initial weight. At slaughter, no interaction effect of protein source and Acacia polyacantha inclusion was observed to influence final weights, slaughter weight, HCW, CCW, commercial DP and real DP (Table 4.13). Likewise, protein source did not influence any of the parameters under pen feeding. Inclusion of Acacia polyacantha in pen feeding diets significantly reduced final and slaughter weights under pen feeding fattening. This could be because the level of Acacia polyacantha used in this experiment raised the quantities of anti-nutritional factors to unbearable levels which consequently affected animal growth. Ulger et al. (2017) reported that high levels of condensed tannins (5% of DM) adversely affects digestibility of nutrients and performance in animals as they reduce protein utilization due to excess formation of tannin-protein complexes. Means of non-carcass components of goats under various pen feeding diets made from either soya bean meal or baobab seedcake with Acacia polyacantha included or not are in Table 4.13. Study results indicate that there was a significant interaction effect of protein source and inclusion of acacia polyacantha on weight of spleen and empty gut. Inclusion of acacia polyacantha in pen feeding diets significantly reduced weights of head, feet, 80 heart, and digestive contents. Source of protein for a diet did not significantly affect weights of non-carcass components or killing-out characteristics (P> 0.05). There was also a significant effect of protein source and inclusion of acacia polyacantha on the proportions of empty gut and spleen to empty body weight, but also the proportion of digestive contents to fasted body weights across the pen feeding fattening diets (Table 4.14). 81 17Table 4.12 Effect of protein source and inclusion of Acacia polyacantha on performance characteristics of local Malawi goats under pen feeding Soya bean Baobab seedcake Without AP With AP Without AP With AP SEM PS AP Inclusion PS x AP Inclusion ADG 67.62b 52.02a 78.45b 54.88a 2.88 0.023 <.000 0.175 Daily DM intake (kg) 0.74 0.69 0.73 0.75 0.02 0.293 0.616 0.087 Total weight gain (kg) 5.68b 4.37a 6.59b 4.61a 0.24 0.023 <.000 0.175 FCR 11.12ab 13.56bc 9.43a 14.18c 0.67 0.433 <.000 0.094 abc Means with different superscripts in the same row differ significantly (P<0.05); SEM= Standard error of mean; PS= protein source; AP= Acacia polyacantha; ADG= Average daily weight gain; FCR= Feed conversion ratio (kg DMI/ kg Wt. gain). 82 18Table 4.13 Effect of protein source and inclusion of Acacia polyacantha on killing out characteristics and Non-carcass components of local Malawi goats under pen feeding Soya bean Baobab seedcake P-Value Without AP With AP Without AP With AP SEM PS AP Inclusion PS x AP Inclusion Body components(kg) Initial weight 11.58 11.52 11.59 11.58 0.81 0.952 0.952 0.965 Final weight 17.08ab 15.56a 18.18c 16.19ab 0.96 0.212 0.014 0.732 Slaughter weight 16.20ab 14.55a 17.14c 15.30a 0.90 0.197 0.01 0.885 HCW 6.82 6.43 7.55 6.94 0.48 0.074 0.149 0.751 CCW 6.61 6.20 7.72 6.71 0.47 0.089 0.157 0.806 CDP 41.14 42.55 42.41 43.72 0.97 0.084 0.055 0.941 RDP 52.30 52.95 53.22 54.44 0.99 0.093 0.19 0.686 Non-carcass components (kg) 83 Soya bean Baobab seedcake P- Value With AP Without AP With AP Without AP SEM PS AP PS X AP Head 1.21 1.08 1.20 1.11 0.07 0.830 0.030 0.710 Feet 0.46 0.40 0.46 0.41 0.03 0.940 0.010 0.740 Skin 0.92 0.86 1.04 0.89 0.08 0.180 0.070 0.440 Empty gut 1.75ab 1.72a 2.00 1.59 0.10 0.380 0.004 0.011 Heart 0.10ab 0.10ab 0.11b 0.08a 0.01 0.700 0.030 0.058 Spleen 0.02 0.03 0.03 0.02 0.00 0.487 0.734 0.020 Liver 0.27 0.27 0.31 0.25 0.02 0.467 0.096 0.148 Lungs 0.23 0.21 0.19 0.21 0.02 0.178 0.676 0.150 Blood 0.39 0.43 0.47 0.41 0.04 0.397 0.686 0.120 Digestive contents 3.18c 2.43a 2.98bc 2.57ab 0.20 0.840 0.000 0.225 abc Means with different superscripts in the same row differ significantly (P<0.05); SEM= Standard error of mean; PS= protein source; AP= Acacia polyacantha inclusion; HCW= Hot carcass weight; CCW= Cold carcass weight; CDP= Commercial dressing percentage; RDP= Real dressing percentage. 84 19Table 4.14 Effect of protein source and inclusion of Acacia polyacantha on proportions of non-carcass components of local Malawi goats (%) Soybean Baobab seedcake P-value Parameter Without AP With AP Without AP With AP SEM PS AP Inclusion PS x AP Inclusion Hot carcass 52.3 52.95 53.22 54.44 0.99 0.093 0.190 0.686 Head 9.26 8.93 8.49 8.75 0.32 0.046 0.887 0.198 feet 3.57 3.30 3.22 3.20 0.15 0.035 0.147 0.229 skin 7.08 7.08 7.31 7.08 0.49 0.733 0.739 0.744 Empty gut 13.46ab 14.20b 14.18b 12.53a 0.53 0.210 0.230 0.003 Heart 0.76 0.81 0.77 0.67 0.06 0.146 0.590 0.109 Spleen 0.18a 0.25b 0.20ab 0.18a 0.02 0.108 0.151 0.012 liver 2.07 2.20 2.18 2.01 0.16 0.751 0.854 0.180 lungs 1.73b 1.79b 1.34a 1.70ab 0.14 0.019 0.037 0.130 Blood 2.99 3.51 3.27 3.21 0.24 0.970 0.173 0.088 Digestive contents 19.75b 16.82a 16.87a 16.88a 0.92 0.037 0.031 0.030 abc Means with different superscripts in the same row differ significantly (P<0.05); SEM= Standard error of mean; PS= protein source; AP= Acacia polyacantha inclusion 85 Inclusion of Acacia polyacantha significantly increased the proportion of lungs to empty weight (P< 0.05) as shown in Table 4.14. The proportion of head and feet to empty body weight was significantly influenced by protein source of pen feeding diets. Generally, soya bean-based diets had higher proportions than those of baobab seedcake-based diets. Higher proportions of non-carcass components could be an indication of lighter body weights. The proportion of lungs to empty body weight among pen feeding diets was significantly influenced by both protein source (P=0.019) and inclusion of Acacia polyacantha (P=0.037). 86 4.3 Effect of pen feeding fattening diets on meat quality 4.3.1Effect of pen feeding fattening diets on temperature and pH changes There was a decrease in both temperature and pH among all five fattening diets just as expected with time after slaughter (Figures 4.2 and 4.3). The control diet had significantly different pH readings at 45 min and 24 h (pHu) from the rest of the diets, which had the same readings during the time readings (Table 4.15). Thus, pH45 and pHu for the control diet was higher (P<0.05) than all the four-pen feeding fattening diets. No notable differences were observed at pH3 and pH6 among all the five diets. Higher ultimate pH in the control (extensively managed animals) can be explained by higher muscle activity and low energy in their diet. As mentioned by Immonen et al. (2000), high metabolizable energy in the diet results in a parallel increase in muscle glycogen levels. Higher glycogen levels result into lower meat pH. This is partly associated with post- mortem glycogen conversion into lactate and hydrogen ions resulting into a decrease in meat pH (Vestergaard et al., 2000). Meat pH is to some degree also related to glycogen levels at slaughter. Animals from extensive systems have been reported to be more prone to pre-slaughter stress compared to those under intensive management which are used to handling and confinement (Muir et al., 1998). Relating this to the current study, it could be concluded that extensively reared goats, in this case the control diet, experienced significant amounts of pre-slaughter stress and this could affect pHu. 87 20Table 4.15The effect of different pen feeding fattening diets on pH and temperature (oC) values of local Malawi goat carcasses Treatments Parameter S SA B BA C SEM P-value pH readings pH45 6.54a 6.55a 6.55a 6.55a 6.60b 0.02 0.003 pH3 6.24 6.27 6.28 6.28 6.28 0.03 0.548 pH6 6.14 6.16 6.15 6.15 6.16 0.01 0.325 pH12 5.75a 5.77ab 5.77ab 5.79ab 5.82b 0.02 0.056 pH24 5.60a 5.65a 5.61a 5.62a 5.71b 0.02 <.000 Temperature(0C) T45 35.62 35.52 35.52 35.53 35.43 0.20 0.915 T3 25.37 25.24 25.4 25.34 25.05 0.16 0.209 T6 20.53 19.97 20.31 20.15 20.15 0.30 0.435 T12 7.24 7.36 7.29 7.14 6.97 0.16 0.129 T24 4.28 4.22 4.27 4.20 4.09 0.07 0.064 abMeans with different superscripts in the same row differ significantly (P<0.05); SEM= Standard error of mean; S = 60% Rhodes grass hay + 40% Soya bean meal based concentrate; SA = 60% Rhodes grass hay + 40% Soya bean meal and Acacia polyacantha leaf meal based concentrate; B= 60% Rhodes grass hay + 40% Baobab seedcake based concentrate; BA= 60% Rhodes grass hay + 40% Baobab seedcake and Acacia polyacantha leaf meal based concentrate; C = Grazing only; T= Temperature at 45 min, 3, 6, 12 and 24h post-mortem. 88 Post-mortem temperature readings of the longissimus thoracis muscle of local Malawi goat weaners from the study were not significantly different amongst the pen feeding diets (Table 4.15). Even though post-mortem temperature was insignificantly different among the diets, the control diet generally had slightly lower temperature readings when compared to the rest of the treatments (Table 4.15). This could be due to thin subcutaneous fat layers (Priolo et al., 2001). 2Figure 4.2 Trends of post-mortem pH for local Malawi goat carcasses under different pen feeding diets. 5.40 5.60 5.80 6.00 6.20 6.40 6.60 6.80 45 min 3h 6h 12h 24h p H v al u es Postmortem time Soybean Soybean + Acacia polyacantha Baobab Baobab + Acacia polyacantha Grazing 89 3Figure 4.3 Trends of post-mortem temperature for local Malawi goat carcasses under different pen feeding diets. 0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45 min 3h 6h 12h 24h T em p er at u re ( 0 C ) Postmortem time Soybean Soybean + Acacia polyacantha Baobab Baobab + Acacia polyacantha Grazing 90 Table 4.16 indicate meat quality parameters of local Malawi goat weaners under different pen feeding diets. Pen feeding fattening diets had no effect on chilling loss and cooking loss in this study (P> 0.05). But then, drip loss significantly differed (P< 0.001) among the diets with the control diet having the highest drip loss percentage. In the present study, chilling loss was slightly above 3% which is normally estimated for goat carcasses (Simela, 2011). Cooking loss results in this study ranged from 23.12 to 23.86%. The results are comparable to Pophiwa et al (2017) who reported a cooking loss range of 17.5 to 25.7% in semimembranosus muscles and longissimus dorsi of Boer and South African indigenous goats. According to Ekiz et al. (2009), water holding capacity (WHC) and cooking loss are closely related with ultimate meat pH. High pH which results into higher net charges and greater space between myofilaments increases water binding capacity and hence, low drip loss and cooking loss (Safari et al, 2011). On the contrary, low ultimate pH results to reduced WHC and increased cooking loss in meat samples (Kadim et al., 2009). Meat from animals under extensive management (control diet), which had higher pHu, had relatively poor WHC (high drip loss) when compared to animals under intensive management (diets other than the control). The control had the highest drip loss (P<0.001). Goats under intensive management had lower drip losses than those on extensive management (Table 4.17). This might be due to higher fat deposition in animals under intensive management which could affect WHC (Karaca et al., 2016). Animals with higher amount of subcutaneous fat have higher water holding capacity because the subcutaneous fat acts as a thermal insulator and avoids excessive evaporation 91 of the liquid when exposed to low temperatures in the cold room (Dallantonia et al., 2015). These results concur with Karaca et al. (2016) who reported high drip loss in pasture fed lambs which had a higher ultimate pH than the concentrate fed lambs. Similar results were also reported by Santos-Silva et al. (2002). Present results indicate that shear force values were significantly influenced by pen feeding diets (P<0.001). Extensively managed goats had WBSF values of 2.63N higher than intensively managed goats (Table 4.17). According to the results of Warner Bratzler shear force values for longissimus thoracis muscle, meat obtained from the control diet was less tender (high Warner Bratzler shear force value) than that from intensive management. Shear force value variation among the diets can be attributed to differences in ultimate pH, fatness level, or a combination of these. Sañudo et al. (2000) observed a decrease in shear force value and toughness with increasing carcass fatness class. On the other hand, endogenous enzyme systems activity is affected by post-mortem pH decline and thus meat tenderness (French et al., 2000). In terms of meat colour, pen feeding diets had significant influence on the LT muscle L* (lightness), b* (yellowness)and Hue values, but not in the a* (redness) and Chroma values. Management system significantly affected meat colour parameters. Intensive production significantly increased L*, b* and hue angle (P<0.05) (Table 4.17). On the contrary, the a* parameter significantly reduced with intensive management (Table 4.17). The control diet had the least L*, b* and hue values. These differences could be attributed to management system which affected pHu. Meat from the control diet was darker (lowest lightness values) than the rest of the diets. This can be attributed to a close relationship between pH and L* reduction. Meat with higher pH is likely to be darker 92 than that with lower pH (Karaca et al., 2016). These results are also consistent with results reported by Diaz et al., (2002); Karaca and Kor, (2015) and Priolo et al., (2002) who reported that the meat in lambs under extensive system is darker than that of lambs under intensive management. Realini et al. (2004) reported that ruminants on high-energy diets had a lighter coloured lean (higher L* values) than those fed low-energy diets. According to Carrasco et al (2009), higher a* values are associated with raised pigmentation depending on increased muscle activity and live weight of the animals and therefore, higher a* parameters in the control diet in the present study could be attributed to increased muscle activity. Goats under pen feeding fattening had significantly higher b* and hue angle (P<0.05) than those under extensive production system. These results were consistent with Karaca et al.(2016) who suggested that such differences could arise due to high ultimate pH in animals under extensive management which had a negative effect on yellowness (b*) and saturation (ho). 93 4.3.2 Effect of pen feeding fattening diets on chilling loss, drip loss, cooking loss, shear force and meat colour of local Malawi goat weaners 21Table 4.16 Effect of pen feeding diets on chilling loss, drip loss, cooking loss, WBSF and colour (L*, a*, b*, Chroma, and Hue angle) of Longissimus thoracis Parameter S SA B BA C SEM P-Value Chilling loss (%) 3.18 3.45 3.69 3.40 3.70 0.41 0.705 Drip loss (%) 0.92a 1.15a 1.51b 1.60bc 1.90c 0.12 <.000 Cooking loss (%) 23.86 23.70 24.35 23.49 23.12 0.62 0.382 WBSF (N) 21.47a 20.75a 21.27a 22.50ab 24.13b 0.74 0.000 Colour L* 38.13ab 38.32ab 41.59b 39.70ab 36.84a 1.30 0.005 a* 12.27 12.56 12.76 12.28 13.14 0.42 0.211 b* 5.33ab 5.10ab 5.68b 4.95ab 4.71a 0.31 0.025 Hue 23.42b 22.15ab 24.17b 22.10ab 19.67a 1.34 0.014 Chroma 13.42 13.60 14.03 13.32 13.96 0.42 0.340 abc Means in the same line with different superscripts are significantly different(P<0.05); L*= lightness; a*=redness, b*= yellowness; SEM= Standard error of mean; WBSF= Warner bratzler shear force; S = 60% Rhodes grass hay + 40% Soya bean meal based concentrate; SA= 60% Rhodes grass hay + 40% Soya bean meal and Acacia polyacantha leaf meal based concentrate; B = 60% Rhodes grass hay + 40% Baobab seedcake based concentrate; BA = 60% Rhodes grass hay + 40% Baobab seedcake and Acacia polyacantha leaf meal based concentrate; C = Grazing only 94 , 22Table 4.17 Effects of production system on meat quality characteristics of local Malawi goat weaners Coefficient Standard Error P-value pH24 -0.15 0.01682 <.000 T24 0.1525 0.05417 0.007 Chilling loss % -0.2659 0.3211 0.412 Drip loss % -0.6024 0.126 <.000 Cooking loss 0.7263 0.4845 0.140 WBSF -2.634 0.6021 <.000 Colour L* 2.5991 1.0477 0.0142 a* -0.6725 0.3335 0.0456 b* 0.5567 0.2471 0.0258 Hue 3.287 1.0615 0.002 Chroma -0.369 0.3353 0.273 Reference category= Extensive production system; pH24= pH at 24 hours; T24= Temperature at 24 hours; WBSF= Warner bratzler shear force; L*= lightness; a*= redness, b*= yellowness. The results in Table 4.18 indicate significant positive correlation on b* and L*; Chroma versus a* and b*; hue and b*; and WBSF versus a* and drip loss. There were also some significant negative correlations in hue and a*; drip loss b*; and drip loss and hue. According to Thomas et al. (2004), there is an inverse relationship between cooking loss 95 of the meat and its drip loss such that an increase in drip loss of a meat sample decreases cooking loss. Even though this inverse relationship was observed in the study, the correlation coefficient obtained from the study was not significant enough to support the theory. There was no correlation between meat ultimate pH and WBSF. 96 23Table 4.18 Pearson correlations for meat quality traits for the longissimus thoracis of local Malawi goat weaners (pooled data). pHu L* a* b* Chroma hue Chilling loss Drip loss Cooking loss WBSF pHu 1 0.03NS 0.08 NS -0.09NS 0.05 NS -0.09 NS -0.10 NS 0.27 NS -0.24 NS 0.20 NS L 1 -0.27NS 0.82*** 0.04 NS 0.88*** 0.19 NS -0.14 NS 0.05 NS -0.11 NS a 1 0.01 NS 0.94*** -0.43** 0.14 NS 0.21 NS -0.13 NS 0.28* b 1 0.35* 0.89*** 0.23 NS -0.28* 0.04 NS -0.08 NS Chroma 1 -0.10 NS 0.20 NS 0.11 NS -0.11 NS 0.23 NS hue 1 0.15 NS -0.34* 0.06 NS -0.19 NS Chilling loss 1 0.19 NS -0.10 NS 0.17 NS Drip loss 1 -0.13 NS 0.49*** Cooking loss 1 -0.05 NS WBSF 1 NS Not Significant; (P>0.05); *(P<0.05); **(P<0.01); ***(P<0.001); L*= lightness; a*=redness, b*= yellowness; WBSF= Warner bratzler shear force; pHu=Ultimate pH 97 4.3.2 Effect of Baobab seedcake and Acacia polyacantha inclusion on meat quality parameters Mean values of ultimate pH, temperature, chilling loss, drip loss, cooking loss, WBSF, and colour of LT muscle of local Malawi goats under different pen feeding fattening conditions are presented in Table 4.19. According to Miller (2002), ultimate pH is the major indicator at commercial level because it may affect important quality characteristics such as colour, cooking loss and tenderness. A combination of many factors such as post-mortem treatment, pre-slaughter handling, glycogen storage and muscle physiology influence the levels of pHu (Ekiz et al., 2012).Pre-slaughter stress causes depletion of muscle glycogen reserves ante-mortem and consequently lead to insufficient meat acidification post mortem which results to high meat pH (Miller, 2002). In the current study, there was no interaction effect of protein source and Acacia polyacantha inclusion on all the meat quality parameters investigated in the study. Results indicated that protein source of intensive fattening diets did not affect (P>0.05) ultimate pH, temperature, chilling loss, cooking loss, shear force value, a*, b*, Hue and Chroma of LT muscle. Temperature, chilling loss, cooking loss, cooking loss, shear force values, L*, a*, hue and Chroma were also not significantly affected by inclusion of A. polyacantha (P>0.05). But then, drip loss and L* significantly differed between protein source. Acacia polyacantha inclusion significantly affected ultimate pH, drip loss, and b*. 98 Inclusion of Acacia polyacantha in intensive fattening diets significantly affected ultimate pH in the LT muscle of local Malawi goats (P< 0.05). Generally, findings from the study indicated an increase in ultimate pH with Acacia polyacantha inclusion. The inclusion levels of Acacia polyacantha used in this study might have affected muscle glycogen levels of animals considering the possibility of animal failure to fully manage the level of tannins present in diets. Condensed tannins (CT) present in Acacia polyacantha could interfere with bioavailability of proteins and energy to animals. According to Ulger et al. (2017), the effect of CTs on the digestibility of nutrients and performance in an animal depends on the amount and biological activity of the condensed tannins and thus, high levels of CTs (above 5% of DM) decrease protein utilization due to excessive formation of tannin-protein complexes. Differences in other mentioned meat quality parameters might also partly be attributed to the existing differences in ultimate pH. 99 24Table 4.19 Effect of protein source and Acacia polyacantha inclusion on meat quality characteristics. Soya bean Baobab seedcake P-value Without A. Polyacantha With A. Polyacantha Without A. Polyacantha With A. Polyacantha SEM PS AP Inclusion PS x AP Inclusion pH24 5.60a 5.65b 5.61ab 5.62ab 0.01 0.317 0.015 0.099 T24 4.28 4.22 4.27 4.20 0.07 0.777 0.224 0.925 Chilling loss % 3.18 3.45 3.69 3.40 0.44 0.462 0.974 0.377 Drip loss % 0.92a 1.15b 1.51c 1.60c 0.08 7.13E-11 0.009 0.228 Cooking loss 23.86 23.70 24.35 23.49 0.63 0.749 0.260 0.434 WBSF 21.47 20.75 21.27 22.5 0.76 0.158 0.638 0.077 Colour L* 38.13 38.32 41.59 39.7 1.42 0.017 0.399 0.301 a* 12.27 12.56 12.76 12.28 0.44 0.741 0.767 0.219 b* 5.329 5.099 5.68 4.954 0.33 0.661 0.044 0.293 Hue 23.42 22.15 24.17 22.1 1.48 0.736 0.113 0.703 Chroma 13.42 13.60 14.03 13.32 0.44 0.605 0.386 0.149 abc Means in the same line with different superscripts are significantly different (P<0.05). PS= protein source; AP= Acacia polyacantha; L*= lightness; a*=redness, b*= yellowness; WBSF= Warner bratzler shear force; SEM= Standard error of means 100 4.4 Profitability analysis Cost and return structure analyses were done to determine the total revenue, total variable costs, gross margins, fixed costs, and net profit of local Malawi goat weaners under the five different treatment groups (Table 4.20). The revenues for the cost and return structure in Table 4.20 were based on an average meat price per Kilogram of K2, 200.00, heads and hooves at K1, 000.00, mixed offal’s at K2, 200.00 and skins at K800.00. Goat housing structures were valued at K530, 000.00 with an estimated life span of 5 years. The cost of procuring water troughs per treatment was K5, 000.00 which was similar to that of purchasing feed troughs. Water and feed troughs used in the experiment had an estimated life span of 5 months. Young animals were valued at K10, 000.00 on average. 101 25Table 4.20 Cost and return structure. S SA B BA C Variable costs (MK) Goat weaners 100,000.00 100,000.00 100,000.00 100,000.00 100,000.00 Concentrate feeding 86,419.74 76,905.86 61,743.04 61,876.37 - Veterinary expenses 10,900.00 10,900.00 10,900.00 10,900.00 17,800.00 Transport costs 3,000.00 3,000.00 3,000.00 3,000.00 3,000.00 wages 5,625.00 5,625.00 5,625.00 5,625.00 - Fixed costs (MK) Depreciation (feeding troughs) 3,300.00 3,300.00 3,300.00 3,300.00 - Depreciation (water troughs) 3,300.00 3,300.00 3,300.00 3,300.00 3,300.00 Depreciation (Housing) 5,300.00 5,300.00 5,300.00 5,300.00 5,300.00 Salaries 48,000.00 48,000.00 48,000.00 48,000.00 78,000.00 Total Variable cost (MK) 205,944.74 196,430.86 181,268.04 181,401.37 120,800.00 102 S SA B BA C Total Fixed costs (MK) 59,900.00 59,900.00 59,900.00 59,900.00 86,600.00 Total cost (MK) 265,844.74 256,330.86 241,168.04 241,301.37 207,400.00 Total revenue (MK) 224,633.96 212,406.86 245,970.00 220,619.55 195,267.50 Gross Margin (MK) 18,689.22 15,976.00 64,701.96 39,218.18 74,467.50 Net profit (MK) -41,210.78 -43,924.00 4,801.96 -20,681.82 -12,132.50 MK= Malawi Kwacha where 1USD= MK 725; S = 60% Rhodes grass hay + 40% Soya bean meal based concentrate; SA = 60% Rhodes grass hay + 40% Soya bean meal and Acacia polyacantha leaf meal based concentrate; B = 60% Rhodes grass hay + 40% Baobab seedcake based concentrate; BA = 60% Rhodes grass hay + 40% Baobab seedcake and Acacia polyacantha leaf meal based concentrate; C = Grazing only 103 4.4.1 Gross Margin analysis Gross margin was calculated by subtracting total variable costs from total revenue (Table 4.20). The positive gross margins suggest that the return on variable costs is higher than the production costs. The control diet (extensively managed animals) had the highest gross margins than all the other fattening diets. Under intensive fattening, baobab-based pen feeding diets had the highest gross margins. Higher gross margins in the control could be a result of lower total variable costs (TVC) because feeding and wage costs were not incurred. In pen feeding diets, wage costs were incurred from the process of hay making. Baobab based diets had the lowest cost of concentrate feeding under pen feeding fattening and this resulted in higher gross margins. However, results in Table 4.18 do not indicate any significant differences in the gross margins amongst the five diet categories. As such, an Analysis of Variance (ANOVA) was conducted to determine any significant variations in the gross margins per animal across the five diets (Table 4.21) There were significant differences (P<0.001) in gross margins per unit amongst the five diet categories (Table 4.21). The control and baobab-based diet had significantly similar per unit gross margins and were the highest. Baobab and Acacia polyacantha-based diet was the intermediate whilst soya bean-based and soybean and Acacia polyacantha-based diets were similar and the least. Protein source significantly affected per unit gross margins (P= 0.001) (Table 4.22). Inclusion of Acacia polyacantha did not significantly reduce unit gross margins. The use 104 of baobab seedcake as a source of protein in formulation of concentrate diets led to higher per unit gross margins. This could be attributed to the fact that baobab seedcake was cheaper than soya bean meal hence reducing the cost of feeding which was one of the critical costs. In this study, animals fed on baobab seedcake-based pen feeding diets produced heavier carcasses as compared to those fed on soya bean meal in their concentrate diets and this led to increased revenues. . 105 26Table 4.21 Treatment means for Gross Margin per unit animal S SA B BA C SEM P-value Per unit Gross margins 1869.00a 1598.00a 6470.00b 3922.00ab 7447.00b 1182.00 1.396E-4 abc Means in the same line with different superscripts are significantly different (P<0.05). SEM= Standard error of mean; S= 60% Rhodes grass hay + 40% Soya bean meal based concentrate; SA= 60% Rhodes grass hay + 40% Soya bean meal and Acacia polyacantha leaf meal based concentrate; B= 60% Rhodes grass hay + 40% Baobab seedcake based concentrate; BA= 60% Rhodes grass hay + 40% Baobab seedcake and Acacia polyacantha leaf meal based concentrate; C= Grazing only 27Table 4.22 Effect of protein source and inclusion Acacia polyacantha on per unit gross margins Soya bean Baobab seedcake Without AP With AP Without AP With AP SEM PS AP Inclusion PSxAP Inclusion Unit gross margins 1869.00a 1598.00a 6470.00b 3922.00ab 1128.00 0.001 0.156 0.249 abc Means in the same line with different superscripts are significantly different (P<0.05). SEM= Standard error of mean; PS= protein source; AP= Acacia polyacantha inclusion 106 4.4.2 Net profit margins Net profit from goat production enterprise was calculated by subtracting total cost from total revenue. Total costs were calculated by adding total fixed costs and variable costs involved in goat production. Apart from baobab-based diets, all other fattening diets including the control had negative net profits which implied that the enterprise was making losses. Baobab based diets had an estimated net profit of aroundK4, 800.00. This could be a result of reduced variable costs of feeding since baobab seedcake as a protein source was cheaper as compared to soybean coupled with higher growth rate and consequently high meat yield under this pen feeding diet. 107 CHAPTER FIVE CONCLUSION AND RECOMMENDATION 5.1 Conclusion The nutritive composition, secondary metabolites and in vitro gas production parameters showed a potentially high CP and energy availability in baobab seedcake, suggesting its possibility of being utilized for ruminant production in the tropics. From the study, A. Polyacantha has the potential to reduce methane production in vitro which could assist in reduction of GHG enteric emission. The present study showed that pen feeding management of local Malawi goats had positive effects on growth performance and weight gains. Pen feeding fattening increased ADG by 38.21 grams per day above that of goats which were just grazing. It also had positive effects on carcass characteristics especially carcass weights. Under intensive fattening conditions, baobab seedcake proved to be a potential source of protein as it did not adversely affect performance and carcass characteristics. In small ruminant diets, baobab seedcake could replace soya bean meal which is expensive but also attracts competition with man and other livestock species especially monogastric animals. Therefore, the use of baobab seedcake under intensive fattening could reduce the cost of feed and optimize the returns from small ruminant production in Malawi. Inclusion of Acacia polyacantha tended to negatively affect growth performance and this study imputed this to reported presence of tannins in A. polyacantha, suggesting that the animals did not tolerate the levels of tannins in the diets. 108 This study suggests that local Malawi goats fattened under intensive conditions are superior to those reared under extensive management system in terms of post-mortem pH decline, drip loss, instrumental tenderness and colour (L*, b*, Hue). The study also showed that animals reared under extensive system have higher pH, darker colour, and lower WHC. Therefore, fattening animals under pen feeding conditions could improve meat quality. Protein source did not significantly affect pH, temperature, cooking loss and tenderness. Inclusion of Acacia polyacantha in intensive fattening diets effected pH, drip loss and b*. This implies that baobab seedcake can be used as a protein source in intensive fattening diets without compromising important meat quality parameters and that intensive fattening could improve some important meat quality parameters of local Malawi goats. With reference to gross margins, all the diet categories had positive gross margins. But basing on net profit margins, only baobab only-based pen feeding diet was profitable with a net profit of around K4, 800.00. The use of baobab seedcake under pen feeding fattening tended to increase profit margins as it had higher revenue and relatively low cost of feeding. As compared to soybean meal-based diets, baobab seedcake only-based diet reduced the feeding cost by around 29%. As such, use of baobab-based concentrates can increase enterprise revenue. Therefore, these findings imply that intensive management of local Malawi goats can be profitable as long as feeding management, which has got a big influence on cost of production, growth of animals and enterprise revenues has been strategically managed to achieve optimal production at lowest cost. 109 5.2 Recommendations Based on the findings from this study, it is recommended that pen fattening of local Malawi goats should be done using non-conventional feed resources with high nutritive content like baobab seedcake in order to achieve better growth performance, carcass and meat quality, and enterprise profitability. It is also recommended that future studies should focus on; 1. In vivo studies to evaluate the potential of A. polyacantha in enteric methane reduction. 2. Study of the growth dynamics of local Malawi goats from birth to maturity. 3. Mineral and anti-nutritional factor composition in baobab seedcake. 4. 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