La croissance du bovin Azawak au Niger : influence de facteurs de variation non génétiques et estimation des paramètres génétiques

Description of the subject. The effects of both non-genetic factors and of genetic parameters on the growth traits of Azawak cattle in Niger were estimated from performance data collected on animals raised in the Toukounous animal breeding station. Objectives. Following on from the results obtained, a model to predict breeding values of breeding stocks is to be developed. Method. The influence of non-genetic factors and of genetic parameters was estimated using a fixed effects linear model and a multi character animal model (REML), respectively. Results. Sex, season and year of birth, and their interactions had a significant effect (p u003c 0.05) on weight from birth to 20 months and average daily gains from birth to 12 months (ADG12) and to 18 months (ADG18). Heritability was moderate for birth weight (0.20) and for weight at 12, 14 and 20 months (0.15 to 0.43), whereas it was higher for weight at 13 months (0.61), ADG12 (0.58) and ADG18 (0.44). Genetic correlations between weights and gains were low to high, and they decreased gradually as the interval between weighing increased. All genetic correlations were positive except those between ADG12 and weight at 17 months and between ADG12 and ADG18. Environmental correlations followed the same trends as genetic correlations. Conclusions. Heritability of weight and gains was moderate to high, indicating that an improvement in meat production could be obtained from selection according to growth performance.