Genetic selection: Evaluation and methods

The ultimate goal of animal selection is to create a new generation of animals that are superior to the current population. Superior is interpreted broadly to include functionality of animals, cost reduction of production, consumer perception, quality of products, and reduced environmental impact. These factors contribute to overall sustainability and long-term economic profitability of animal production. An essential element of selection is a genetic evaluation system for the detection of superior animals to be used to produce future generations. Current genetic evaluations use phenotypic records and advanced statistical methods to separate genetic and environmental effects. These traditional methods are complemented by DNA-based technologies that provide genetic information at a molecular level. Genetic evaluation systems are highly complex and involve collection of data from thousands of farms, determination of milk characteristics in laboratories, processing and storage of data in regional computing centers, and application of advanced statistical procedures to estimate genetic merit. Genetic evaluations are widely distributed and are the primary determiner of the value of semen and embryos. Internationally, bull evaluations are combined across countries so that each country has a single national ranking of all bulls worldwide. Selection decisions on farms and by artificial insemination organizations are highly dependent on that genetic information. This article covers aspects of genetic selection that stretch from basic data collection (including identification systems), traits recorded and evaluated, and characteristics of current and future evaluation systems to new DNA-based technologies.