ASC-222: Crossbreeding Considerations in Sheep

This is an oversimplification, but it will work for this discussion. An animal’s phenotype is observed or measured, but the animal’s breeding value is what is of interest to the sheep breeder. Unfortunately, it is not possible to know the true genetic merit of an animal for a particular trait. Therefore, in order to make selection decisions, its breeding value must be estimated. The animal’s own performance is one indicator of its breeding value. The usefulness of individual information depends on the proportion of the differences in performance between animals that is due to differences in breeding values. This difference is called the heritability of the trait: