Animals can be genotyped for thousands of single nucleotide polymorphisms
(SNPs) at one time, where the SNPs are located at roughly 1-cM
intervals throughout the genome. For each contiguous pair of SNPs
there are four possible haplotypes that could be inherited from the sire.
The effects of each interval on a trait can be estimated for all intervals
simultaneously in a model where interval effects are random factors.
Given the estimated effects of each haplotype for every interval in the
genome, and given an animal’s genotype, a ‘genomic’ estimated breeding
value is obtained by summing the estimated effects for that genotype.
The accuracy of that estimator of breeding values is around 80%.
Because the genomic estimated breeding values can be calculated at
birth, and because it has a high accuracy, a strategy that utilizes these
advantages was compared with a traditional progeny testing strategy
under a typical Canadian-like dairy cattle situation. Costs of proving
bulls were reduced by 92% and genetic change was increased by a factor
of 2. Genome-wide selection may become a popular tool for genetic
improvement in livestock