INHERITANCE OF GROWTH AND LACTATION PARAMETERS IN YANKASA SHEEP

Résumé

Estimates of genetic and phenotypic parameters for lactation records of 143 ewes and growth performance of 134 lambs were examined using the paternal half-sib mixed model analysis. Heritability (h2) estimates for the curve parameters were 1.4, 0.3, 0.2 and 0.5 for a (level of general production), b (pre-peak curvature), c (post-peak curva-ture) and total lactation (T). The estimates of phenotypic and genetic correlations between the various curve parameters were mostly positive and moderate in magnitude. For the growth parameters, h2 estimates of 0.3 and 0.7 were obtained for birth weight (BWT) and 90- day weaning weight (WWT) respectively. The genetic and phenotypic correlations between these traits were 0.7 and 0.3 respectively. In conclusion the moderate estimates of h2 obtained for curve parameters in this study indicate that improvement of milk production performance of the Yankasa sheep through selection is possible. Similarly, the magnitude of the estimate of correlations between BWT and WWT probably indicates that selection based on BWT will improve WWT. Furthermore, preliminary, culling based on BWT is also possible.