The genetics of temperament traits in merino sheep

Abstract

Investigations were made into the genetics of temperament in Merino ewes, with emphasis on those aspects which might have associations with maternal behaviour and postnatal survival of lambs. A data set of over 2000 animals and more than 20,000 records was analysed for estimation of genetic parameters. The heritability of ewe mothering temperament was 0.39 ± 0.02, indicating a moderate genetic component to this behavioural trait. Agitation score and flight time were less heritable (0.20 ± 0.05 and 0.12 ± 0.05 respectively). The heritability of litter survival was low (0.09 ± 0.01) and the genetic correlations between this and ewe mothering temperament, agitation score and flight time were 0.18 ± 0.08, 0.39 ± 0.18 and 0.09 ± 0.27 respectively. Estimated genetic correlations between temperament traits and wool traits were low, with the exception of staple length, which was negatively genetically correlated to agitation score (rg = -0.26 ± 0.03). These results suggest that if temperament is used as a selection criterion, although no antagonistic results will be seen in wool production, there would be no advantage in litter survival compared with undertaking direct selection for the trait. Further, if selection is practised for low agitation score, our results suggest that litter survival may be slightly reduced in future generations.