The role of biology in future pig breeding programs.

Swine breeders and producers have as their primary objective the efficient production of quality pork. Meeting this objective has required that both the breeder and producer manipulate the biology of the pig. In the past, the tools available to the swine producer to manipulate the biology of the pig were limited to good management practices and proper nutrition. The swine breeder was limited by the traits he could measure phenotypically and by the use of selection and mating systems. In many respects the primary limitations to further genetic improvement were the lack of sufficient biological knowledge about a specific t rai t and the means to more efficiently change i t . Today new biotechnological tools are becoming available. These tools include methods that allow gene identification, cloning and manipulation, embryo and semen sexing, production of transgenic animals and measurement, genetic evaluation and selection of traits previously not considered. These tools and the use of a variety of swine germplasms not only will increase the rate of genetic improvement but will increase the knowledge of the biology of the pig and will enhance our abil i ty to manipulate that biology to produce pigs more ef ficiently and humanely.