Genetic parameter estimation of preweaning growth traits in Akkaraman sheep.

Abstract

This study aimed to evaluate (co)variance components and heritability of pre-weaning body weight traits and the Kleiber ratio in Akkaraman sheep. Data collected between 2018 and 2023 from Çankırı province, Türkiye, formed the basis of this research. The considered traits were birth weight (BW), weaning weight (WW), average pre-weaning daily weight gain (ADWG), and Kleiber ratio (KR). Utilizing animal mixed models and the average information restricted maximum likelihood (AI-REML) procedure, genetic parameters were estimated. Direct heritability estimates were 0.30 ± 0.02, 0.23 ± 0.02, 0.23 ± 0.02, and 0.28 ± 0.03 for BW, WW, ADWG, and KR, respectively. Maternal genetic heritabilities were 0.03 for WW and 0.02 for WW, ADWG, and KR. Direct genetic correlations among pre-weaning growth traits were negative for BW-WW and BW-ADWG and positive for WW-ADWG at -0.05, -0.23, and 0.98, respectively. The moderate direct heritability estimate suggests the presence of genetic variability in the Akkaraman sheep breed, indicating potential genetic progress through selective breeding. Despite the low maternal permanent environmental effects, the significant impact of maternal care on lamb growth in this breed underscores the importance of considering both direct and maternal effects in the genetic evaluation of early growth traits. The observed negative genetic correlations among birth weight, weaning weight, and daily live weight gain until weaning emphasize the need for careful consideration in selection programs for the Akkaraman breed.