Abstract
Microinjection of DNA that contains genes into the pronuclei of zygotes from pigs, sheep, cows and goats has resulted in the production of “transgenic” livestock containing new genetic material that can be transmitted from one generation to the next. Transgenic livestock are possible because recent advances in molecular biology allow the novel recombination of DNA fragments, thus permitting the introduction of transgenes with novel regulation and/or products. These technological advances have been utilized in agriculture to explore the possibilities of enhancing growth characteristics, mammary gland function, and disease resistance in livestock.