Estimates of (Co)-Variance Components and Genetic Parameters for Growth Efficiency Traits by Animal Model in Chokla Sheep.

This study obtained genetic data from pedigree records of Chokla lambs over 47 years (1974-2020) and 6785 records of performance were available at Central Sheep and Wool Research Institute, Bikaner, Rajasthan, India. (Co)variance components and genetic parameters of average daily gain and Kleiber ratio were estimated by average algorithm restricted maximum likelihood (AIREML), fitting six different animal models with various combinations of direct and maternal effects. Direct heritability estimates were inflated substantially for all traits when maternal effects were ignored. The direct additive heritability h² values for all ADGs and KRs were moderate (0.3-0.4). The maternal influence diminished as age increased and found to be important and sizeable at pre-weaning stage. Negative and high estimate of covariance between direct and maternal effects, resulted highly inflated values of additive heritability. To avoid using skewed estimates of additive heredity in this situation, it is more beneficial to evaluate the response for selection based on phenotypic values using total heritability (h² t ). If lambs are chosen for greater feed efficiency based on KR, there may be scope for indirect selection for growth rate, according to positive correlations shown between ADG and KR. [ABSTRACT FROM AUTHOR]

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