Genetic parameters for growth traits in N'Dama cattle under Tsetse challenge in The Gambia. In Genetic improvement of livestock in Tsetse infested areas in west Africa
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Permanent link to this item: http://hdl.handle.net/10568/70949
Heritabilities and correlations for growth traits in N'Dama cattle under tsetse challenge were estimated using an animal model. Animals were born and weaned in a low to medium tsetse challenge area and, after weaning at 12 months of age, they were transported to a high tsetse challenge area until three years of age. Measurements included body weight and growth rate during seasons from 12 to 36 months of age. Two seasons were defined: the dry season from November to June representing the period of feed shortage and low tsetse fly density; and the wet season from June to November where sufficient feed was available and the tsetse density was the highest. Heritabilities for body weight ranged from 0.28 for body weight at 36 months of age to 0.48 for body weight at 15 months of age. For growth rate, the heritability was 0.09 during the dry season and 0.15 during the wet season. Genetic correlations of birth weight with body weight at 12 and 15 months of age were moderately high (0.49 and 0.51, respectively). Genetic correlations between most body weights and growth rates during seasons ranged from –0.40 to 0.80. The genetic trend due to the selection programme was highest for body weight at 36 months of age from 1994 to 2004. For growth traits, an increasing genetic trend was observed in growth between 15 and 36 months of age and in growth during the dry season from 12 to 36 months of age. It was concluded that selection for growth should focus on growth during dry and wet seasons. Keywords: genetic correlation, genetic trend, heritability, selection, tropical cattle.