Breeding means generating offspring that are better than their parents. Parents just pass on their genetic makeup. They should be selected based on genetic merit rather than on observed performance/traits. Relevant traits for dairy cattle breeding are influenced by several genes.

Each offspring receives one half of the genes from the father and the other half from the mother. As a parent does not pass the same set of genes on to all calves, there are significant differences between half and full siblings.

Estimated breeding values (EBV) are an attempt to classify information on all observable phenotypic traits into two components: genetics and environment.

Phenotype = genetics + environment

The breeding value (BV) is an estimated value expressing the genetic predisposition of an animal to a specific trait. Mathematically, the real EBV of an animal – according to the theory of population genetics – can be expressed as follows:

Breeding value = 2 x (NKD – PD)

(NKD = average offspring performance)
(PD = reference population average)