The effect of graded level replacement of noug seed cake with local brewery residues on reproductive performance of Bonga sheep in Kaffa Zone, Southwestern Ethiopia

The study's objective was to evaluate the effect of graded-level replacement of noug seed cake with local brewery residues on the reproductive performance of Bonga sheep. Forty-eight Bonga ewes (2 -3 BCS and 22 – 37 kg of body weight) grazing on natural pasture were randomly assigned to supplementary treatments consisting of combinations of ‘Areke Atela’ and commercial concentrate (CC): T1 (0 g ‘Atela’ + 450 g CC), T2 (45 g ‘Atela’ + 405 g CC), T3 (90 g ‘Atela’ + 360 g CC), T4 (135 g ‘Atela’ + 315 g CC), T5 (180 g ‘Atela’ + 270 g CC) and T6 (control). The experimental design was a randomized complete block design (RCBD) with eight blocks consisting of six ewes per block based on their body weight and body condition score. The sampled ewes were only targeted at Bonga agriculture institution CBBP site owned by breeding program cooperative members and the study spanned 170 days with an additional 15-day adaptation phase, conducted in the Adiyo district Boka village, Kafa zone, southwest Ethiopia region, from 10 August 2023 to January 2024. After feeding for 15 days as an adaptation period, the estrous cycle was synchronized with two intramuscular injections with 11-day intervals, 5 mg PGF2α, before artificial insemination. Semen was collected from top rams using artificial vagina at the day of ewe’s estrus response and immediately inseminated. A general linear model (GLM) procedure of the statistical analysis system (SAS, version 9.3) was used to analyze body weight, body condition score, onset of estrus, duration of estrus, lambs birth weight, litter size, and gestation period. The estrus response rate, conception rate, and lambing rate was analyzed using nonparametric test. The result showed that, the replacement groups significantly increased (p < 0.05) at T2, and T3 demonstrated superior estrous response and pregnancy rate compared with T4,T5 and the controlled group T6. Replacement group (T2, T3) with 45 g Areke Atela + 405 g CC and 90 g Areke Atela + 360 g CC are promising economical feed replacement to increase the reproductive performance of Bonga ewes.