Abstract

Realised rates of genetic improvement depend upon structural, technological, economic and cultural factors. The potential nature and rate of genetic improvement of livestock has largely been dictated by accuracy of the predicted genetic merit of selection candidates. Major milestones in predicting merit include the use of objective measurements rather than visual appraisal; adjustment of measured performance for nongenetic factors; use of aggregate measures of economic merit for multiple trait selection; combining of information from all available sources of relatives and traits; and properly accounting for previous selection. Despite these advances, use of pedigree and performance information has major limitations. Genomic technologies can trace inheritance of chromosome fragments and with knowledge of the fragment values can improve accuracy of prediction in young selection candidates. Current genomic methods perform more poorly with real than with simulated data, and predictive abilities erode when applied to target animals not closely related to the population used to quantify fragment values. Several strategies are being investigated to improve genomic predictions, but in the meantime the principal benefit of the technology has been to increase accuracy of predicted merit of young selection candidates for routinely measured traits. In some cases this has reduced the generation interval.

DJ, Garrick

Proceedings of the New Zealand Society of Animal Production, Volume 70, Palmerston North, 104-112, 2010