(CO)Variance components and genetic parameters of pre- weaning growth traits and Kleiber ratio in Bharat Merino sheep

(Co)variance components and genetic parameters of pre-weaning growth traits and Kleiber ratio were estimated in Bharat Merino sheep by restricted maximum likelihood, with different combinations of direct additive genetic and maternal effects, fitting a total of six animal models. The data consisted of 9215 animals for birth weight (BW) and 7786 animals each for weaning weight (WW), average daily gain (ADG) and Kleiber ratio (KR), spread over a period of 44 years (1975–2018). The estimates of direct heritability BW, WW, ADG and KR were 0.11±0.02, 0.28±0.03, 0.28±0.03 and 0.38±0.03, respectively.The direct heritability estimates were moderate to moderately high and at the same time, maternal effects contributed significantly to the sources of variations among individuals. From bivariate analysis, pair-wise genetic correlations were positive and high between WW and ADG (0.98±0.00), WW and KR (0.91±0.01) and ADG and KR (0.96±0.00) pairs, suggesting similar underlying genetic factors influencing these traits. It was concluded that whenever estimating (co)variance components and heritability of early growth traits, maternal effects must be included in the model. Thus, the correct approach for selection would be selecting animals on basis of their breeding values aftertakinginto accountmaternaleffects.