Genetic parameters for growth traits of the Moroccan Timahdit breed of sheep.

Data from 522 lambs of the Timahdit breed representing 13 sires were used to estimate genetic parameters. Traits analyzed were weights at birth (BW), 30 days (W30), 70 days (W70) and 90 days (W90), average daily gains from 10 to 30 days (ADG10-30), 30-70 days (ADG30-70) and 30-90 days (ADG30-90). REML estimates of variance and covariance components were obtained assuming animal models that included the fixed effects of sex, age of dam and the combined effect of year and types of birth or rearing, and the animal random effects for the direct and the maternal genetic effects. Genetic correlations were estimated with the same fixed effects and only additive direct genetic effects. Results showed that an important direct additive and maternal genetic effects were observed. Estimates of the direct heritability and maternal heritability were respectively 0.18, 0.59 (BW); 0.31, 0.34 (W30); 0.50, 0.24 (W90); 0.42, 0.08 (ADG10-30), and 0.31, 0.22 (ADG30-90). Estimates of additive direct-maternal correlations were important and ranged from -0.94 to -1.0 for live weights, and from -0.70 and -1.0 for daily gains. The estimates of genetic and phenotypic correlations were high and showed no genetic antagonisms among the growth traits.