Evaluation of Genetic and Maternal Effects on Growth-Related Traits in Sonadi Sheep

Efficient growth in indigenous sheep breeds is vital for improving livestock productivity and sustainability in arid and semi-arid regions. Sonadi sheep, a native breed of Rajasthan, India, play a crucial role in the rural economy; however, comprehensive genetic evaluation of their growth-related traits is lacking. This study aimed to estimate genetic parameters and correlations for key growth-related traits, average daily gain (ADG), Kleiber ratio (KR), growth efficiency (GE), and relative growth rate (RGR), across different growth phases to support selection strategies in Sonadi sheep. Data from 1,834 lambs born between 2010 and 2024 in a structured nucleus breeding herd were analyzed. Traits were measured across three age intervals: 0–3 months (pre-weaning), 3–6 months, and 6–12 months (post-weaning). Six animal models incorporating direct and maternal genetic effects were evaluated using restricted maximum likelihood (REML) procedures. The best-fitting model for each trait was identified based on the Akaike Information Criterion (AIC) and log-likelihood values. Direct heritability estimates ranged from 0.09 to 0.28 for ADG, 0.18 to 0.33 for KR, 0.24 to 0.31 for GE, and 0.23 to 0.33 for RGR, suggesting moderate-to-high genetic control. Maternal heritability also declined with age (0.04–0.26). Strongly negative direct–maternal genetic correlations, particularly during the pre-weaning stage, indicate genetic antagonism between lamb performance and the dam’s maternal environment. The genetic correlations among the traits were consistently high (0.96–0.98), whereas the phenotypic correlations were slightly lower (0.91–0.95), reflecting a shared genetic basis. Significant non-genetic influences included sex, lambing season, and dam weight at lambing. This study confirmed the presence of substantial additive genetic variance in growth-related traits of Sonadi sheep and identified antagonistic maternal effects that must be addressed in genetic evaluations. High genetic correlations among early life post-weaning traits suggest that multi-trait selection strategies could simultaneously improve early growth and feed efficiency. These findings offer practical guidance for breeding programs targeting sustainable meat production under challenging environmental conditions in arid regions of India.