Estimation of Genetic Parameters for Reproduction Traits in Munjal Sheep

Abstract

Estimates of genetic parameters are important to determine the selection criterion and future breeding strategies. Munjal is one of the heaviest breed of sheep and is popular among farmers for faster growth rate and efficient reproduction. The data of reproduction traits of 287 Munjal sheep maintained at Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar for 16 years (2001-2016) were utilized to estimate the genetic parameters. The mixed linear model used for analysis included the sire as a random effect and period of birth and dam’s age at lambing as fixed effects. Heritability and genetic correlations for different traits were estimated by paternal half-sib correlation method using sire components of variance and covariance. All the reproduction traits under study viz., Age at first service (AFS), weight at first service (WFS), age at first lambing (AFL), weight at first lambing (WFL) and first lambing interval (FLI) were significantly affected by period of birth. However, effect of dam’s age at lambing was non-significant on all traits. The overall least squares mean for AFS, WFS, AFL, WFL and FLI were estimated as 563.08±14.43days, 29.06±0.16 kg, 713.48±14.02 days, 31.30±0.16 kg and 351.82±1.12 days, respectively. Heritability estimates for AFS, WFS, AFL, WFL and FLI were obtained 0.19±0.12, 0.24±0.15, 0.17±0.10, 0.27±0.15 and 0.05±0.01, respectively. The genetic correlation of AFS with AFL (0.96±0.01) and WFS with WFL (0.94±0.03) was high and positive indicating that ewes in good body condition at service maintaining it after lambing. Low estimates of heritability for reproduction traits indicated that these traits have low additive genetic variance and mostly influenced by environment. So, these traits can be improved by better managemental practices.