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.