Since Robert Bakewell made the observation that like begets like, animal breeders have been attempting to better define what we like. For the most part, we have divided selection into two parts, genetic prediction of breeding values for individual traits and combining those predictions into multi-trait selection criteria to maximize progress towards the breeding objective. Technology is well advanced in predicting the transmittable genetic component of traits. Given a database of pedigree information and observed phenotypic performance, we can predict accurate and unbiased breeding values. Through the use of profit functions, we have effective tools to describe selection objectives. Procedures have been developed to consider complicating issues such as opportunity costs, genetic lag, market elasticity, non-linear values, restrictions to change, risk and competition. We can even integrate mating systems and use of multiple genetic lines in mating programs into our objectives. A summary of selection criteria being applied around the world is presented. What is obvious as the limitation in those applied programs is our lack of data recording programs for all traits of economic importance. For some traits, such as reproductive efficiency and longevity, it is just a simple matter of more comprehensive data recording. But for other traits, such as carcass quality, we do not fully understand the biological processes that control and define the trait or have accurate phenotypic measures of the trait. Therefore can not access the trait in sufficient numbers of selection candidates to generate reasonable selection intensities. And ultimately, genetic improvement is dependent on how much selection intensity we generate and where we direct it.

T. S Stewart

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 25: Lactation; growth and efficiency; meat quality; role of exotic breeds in the tropics; design of village breeding programmes;, , 327–334, 1998
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