Genetic parameter estimates for birth weight, weaning weight and average daily gain in pure and crossbred sheep in Ethiopia

Data for birth weight (BW), weaning weight (WW) and pre-weaning average daily body weight gain (ADG) of seven different genotypes of lambs (pure Awassi (A), n = 80, pure local (L), n = 3300, lambs with 10 to <50% A x L n = 137, 50% A x L n = 1142, >50 - <75% A x L n = 273, 75% A x L n = 800, and >75% A x L n = 904) were used to estimate genetic parameters. Fixed effects included in the model were genotype (with or without), type of birth, sex, season x year of birth combination. All fixed effects were significant. (Co)variance component estimates were obtained from bivariate animal model analysis including maternal genetic and maternal permanent environmental effects. Direct additive (co)variances and correlations among the traits were positive. Genetic antagonism existed between direct and maternal effects for all traits. Direct heritabilities (h) for BW, WW and ADG were 0.39, 0.33 and 0.25 (with genotype) and 0.28, 0.31 and 0.25 (without genotype). The corresponding maternal heritabilities (h) were 0.13, 0.18 and 0.19 and 0.19, 0.18 and 0.18, respectively. Both, maternal genetic and maternal permanent environmental effects were important.