Genetic Evaluation and Relationship Across Ages for Dag Score in Maternal Sheep

Abstract

Daginess in sheep is an undesirable trait with both economic and welfare implications. While the trait has been investigated in Merino sheep, this is not the case for maternal sheep. With sufficient records now available from industry and research flocks via Sheep Genetics the genetic parameters for dag score can now be estimated. The heritability of dag score ranged from 0.13 (+0.01) to 0.38 (+0.02) across age stages with the highest heritability occurring at the yearling stage. Given the heritability it should be possible for breeders to make genetic progress towards less daggy maternal sheep, which as an indirect selection tool will potentially assist to reduce labour costs, wool losses and flystrike incidence. Positive moderate genetic correlations between age classes (0.08 to 0.83) indicate that selection based on phenotypes recorded at any age will lead to reduced dag score across investigated stages. The results suggest that breeders should be focussed on recording dag score when the environmental conditions promote the greatest expression of genetic merit, than scoring at a specific age class. However, in maternal sheep the greatest phenotypic variation in dag score appears to occur in yearling sheep.