Estimates of covariance components and genetic parameters for growth, average daily gain and Kleiber ratio in Harnali sheep

摘要

The aim of the present study was to estimate the (co)variance components and genetic parameters for various growth traits (weight at birth (BWT) and 3 (WT3), 6 (WT6), 9 (WT9), and 12 (WT12) months of age), average daily gain (ADG1, 0-3; ADG2, 3-6; and ADG3, 6-12 months of age), and Kleiber's ratio (KR1:ADG1/WT3(0.75)and KR2:ADG2/WT6(0.75)) by using records of 526 lambs of 41 sires and 186 dams in Harnali Sheep maintained at Department of Animal Genetics and Breeding, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar (Haryana), India for the period of year 2014-2019. Restricted maximum likelihood procedure (REML) was employed for estimation of covariance components and genetic parameters by considering direct effects with or without maternal effects. The estimates of direct heritability for BWT, WT3, WT6, WT9, WT12, ADG1, ADG2, ADG3, KR1, and KR2 were 0.10, 0.45, 0.32, 0.36, 0.23, 0.43, 0.02, 0.001, 0.38, and 0.02, respectively. It was observed that maternal effects had significant influence on BWT trait only, and corresponding estimate of maternal heritability was 0.16. This indicated the importance of maternal ability in Harnali sheep for initial growth performance. Moderate estimate of direct additive heritability of weaning weight (WT3) and moderate genetic correlations of it with other traits indicated that the current practice of selection at 6 months may be replaced by early selection at WT3 in order to improve the growth performance in Harnali sheep.