Exploring Genotype x Environment Interaction and Heritabilities for a Reproduction Trait in Merino Sheep Using Three Approaches

Three approaches were used to detect genotype x environment (GxE) interaction and estimate heritabilities for "number of lambs born" (NLB) in Merino progeny of the Sheep CRC Information Nucleus Flock. Approaches included a univariate model, fitting site x sire interaction as a random effect and a bivariate model that treated NLB expressed at high and low pre-joining condition score as two genetically separate traits. The third approach was a random regression sire model that regressed NLB on mean deviation in pre-joining condition score at each experimental site from the overall mean of all sites. All approaches indicated that there was no significant GxE interaction for NLB. The consistently low heritabilities across all approaches also reflected that they did not differ in the partitioning of the variance components.