Regulation of estrus and ovulation in sows

摘要

Controlled release compositions and methods for inducing pseudopregnancy in gilts and sows are disclosed. In the preferred embodiment, the formulation includes polylactide microspheres releasing estradiol 17 beta at physiologically useful levels over a period of time between five and thirty days. Following induction of pseudopregnancy, the pseudopregnancy can be terminated and estrus induced by administration of a compound such as PGF2 alpha . The advantages of inducing pseudopregnancy followed by induction of estrus are that the breeding patterns of large numbers of gilts and sows can be controlled.