Estimation of genetic parameters and breeding value of body weight at different stages of Hu sheep growth and development and genetic correlations with key feed efficiency indices

In this study, we sought to determine variance components and genetic parameters for the body weight traits of Hu sheep at different stages of growth and development, thereby providing a reference for Hu sheep breeding. In 2018 and 2019, we selected new-born male Hu lambs with complete pedigree records, and used the birth weight, weaning weight, and 100- and 180-day body weights to determine the feed intake from 100 to 180 days of age. Variance components were estimated based on a restricted maximum likelihood algorithm using ASREML-R, and body weight breeding values were estimated based on the best linear unbiased prediction at each test period. The results revealed that the variance of maternal permanent environmental effects was significant at different body weight stages (P < 0.05). The estimated heritabilities of birth weight, weaning weight, and body weight at 100 and 180 days of age were 0.43, 0.27, 0.46, and 0.41, respectively. The genetic and phenotypic correlations between different body weights ranged from 0.38 to 0.97 and from 0.25 to 0.84, respectively. The genetic and phenotypic correlations between feed conversion rate and body weight were 0.09 ~ 0.74 and 0.05 ~ 0.51, respectively, whereas the genetic and phenotypic correlations between residual feed intake and body weight ranged from −0.04 to 0.26 and from −0.15 to 0.039, respectively. We concluded that in Hu sheep, maternal effects have an important influence on the growth rate of lambs. Medium and high body weight heritability were identified at different growth stages, whereas we detected large differences among the genetic and phenotypes correlations between selected feed efficiency traits and body weight at different growth stages. Accordingly, careful selection at an early stage is necessary to reduce potential losses in economic benefits. If selection is practiced at an age of 100 days, improvement would be seen at an age of 180 days.