Estimating the genetic merit of all individuals in a herd is required before a comprehensive selection and genetic improvement program can be successful. Performance records need to be
collected on as many animals as possible, ideally on every animal in the herd. Since animals have relatives and progeny in the herd, the records on these relatives or groups of relatives can be
used to improve the estimation of the genetic merit of an individual animal.
Animals are related when they receive some identical genes from a common ancestor. When they have genes in common, the performance of one individual for a given trait can be used to help
estimate genetic merit for other related individuals.
Genetic evaluations conducted by the majority of breed organizations and breeding stock companies use the animal model and best linear unbiased prediction (BLUP) procedures. This technology is used to determine expected progeny differences (EPDs) for the animals evaluated. An EPD is the predicted average performance difference of the offspring from a breeding animal compared to the average performance of the offspring from other animals in the same population. The animal model not only uses
the individuala