Effect of Different Data Exclusion Policies on the Heritability of Fat Depth in Maternal, Merino and Terminal Sheep

Abstract

The effect of different data exclusion policies for post weaning fat depth on heritability estimates were examined using industry data for Maternal, Merino and Terminal sheep. The exclusion policies which had the most positive effect on heritability were mean fat depth for the contemporary group (CG), and standard deviation of fat depth for the contemporary group. Exclusion based on mean weight of the CG showed some effectiveness for light animals. Excluding records based on mean age of the CG had no effect on heritability estimates. In order for fat depth to be analysed most appropriately animals should be measured when they have had the opportunity to express the trait. It is appropriate to exclude CGs from the analysis where the variation in fat depth for a CG is low to improve heritability. The impact of these data exclusions on the utility of breeding values would need to be investigated in each analysis before any policies can be implemented.