Genetic aspects of puberty in Awassi ewes

Abstract

Body weight at puberty (WP), age at puberty (AP), weaning weight (WW) and growth rate from weaning to puberty (GR) in Awassi ewe lambs were studied. Average age of Awassi ewe lambs at first estrus was 278.9±6.3 days, their average body weight was 30.0±0.2 kg and represents 61% of adult body weight. Heritability estimates for AP and WP were 0.35±0.06 and 0.26±0.08, respectively, and indicate that improvement through selection would be effective. Genetic and phenotypic correlations between (WP) and (AP) were −0.65 and −0.37, respectively. Genetic and phenotypic correlations between AP and each WW and GR indicate that selection on the basis of WW or/and GR would also result in genetic improvement for AP. The same results have also been shown with WP. Genetic progress in WP and AP could be 0.27 kg more and 6.03 d less per generation through mass selection. The conclusion from this work is that genetic improvement, in addition to better feeding and management, offers the opportunity to increase output from existing resources through breeding from ewe lambs, extending production life of the ewe, and shortening the generation interval, thus accelerating genetic improvement.