Validation of breeding values for robustness in Australian Merinos

Livestock production often involves raising animals in environments which can vary substantially between locations and years. It could be beneficial to select animals that have genetic merit which is more robust to environment variation, rather than animals that are more sensitive. This study attempts to validate breeding values for robustness estimated using reaction norm models. Reaction norm models were used to regress breeding values for body weight across different growth environments in the Information Nucleus Flock. The same model was fit to MERINOSELECT data, and the rank-correlation for EBVs of sires with progeny in both datasets was calculated. The pattern of genetic variance and heritability across environments was very similar between datasets. The rank correlation of breeding values for a subset of sires with the best distribution of progeny in both populations was 0.60, 0.22 and 0.17 for the intercept, slope and scale-corrected slope, respectively. The results indicated that the genetic variation in robustness across growth environments was, to some extent, repeatable across the two datasets. Genotypes that re-ranked more in the INF/RF also tended to re-rank more in MERINOSELECT, although the relationship was weak. The analysis could benefit from the inclusion of genomic data to increase linkage across environments and between datasets.