Abstract: A method for synchronizing ovulation in sows and gilts by a single injection of hormones is disclosed. A hormone, gonadotropin releasing hormone (GnRH), luteinizing hormone (LH), follicle stimulating hormone (FSH), human chorionic gonadotropin (hCG), analogues, derivatives, agonists or combinations thereof is administered to an open sow post weaning at a specific time to stimulate ovulation of mature responsive follicles. The sow is then bred, without heat detection, at a specific subsequent timed interval after injection with hormone, with one or two artificial or natural breedings. In gilts, the hormone is injected at a timed interval from onset of estrus or at a specific timed interval following Prostaglandin F2a for those gilts which have been held in a state of pseudopregnancy.

Abstract: 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.