Genotyping reduces preselection bias on MERINOSELECT ASBVs in Merino flocks

Preselection of breeding animals to reduce the costs of phenotyping can lead to selection bias resulting in the loss of accuracy of Australian Sheep Breeding Values (ASBVs). This paper used a subset of data from the MERINOSELECT database to quantify the effects of selection bias in flocks with varying methods of preselection including random and selected phenotyping both with and without genotype information. Results show that genotyping all animals in combination with phenotyping the top 50% of animals based on genotype provided the most accurate individual and sire ASBVs. However, whilst this was the most accurate scenario, it still involved loss of ASBV accuracy and selection bias that varied according to trait when compared with the current model that includes genotyping and measuring all animals prior to selection.