The administration of hormones to control the reproductive process in domestic mammals such as horses, sheep, pigs, cows (bovine) and goats is well known in the art. One approach to managing reproductive processes in domestic mammals involves the direct administration of gonadotropins to domestic animals. Gonadotropins are produced by the anterior lobe of the pituitary gland and are characterized as follicle stimulating hormone (FSH) and luteinizing hormone (LH). Typically such hormones are extracted from porcine pituitary glands and employed in cattle or other domestic animals to control or enhance the ovulatory process. One gonadotropin preparation is the follicle stimulating hormone FSH-P available from Schering-Plough Corp. FSH-P has a relatively high and variable content of luteinizing hormone, and while effective in producing an ovulatory response, is less than desirable in terms of fertilization rates and production of transferable embryos. Another formulation which is effective in producing superovulation in cattle comprises a follicle stimulating hormone composition which contains a low, controlled amount of luteinizing hormone to produce a high ratio of follicle stimulating hormone to luteinizing hormone. This composition is disclosed in U.S. Pat. No. B1 4,780,451 to Donaldson.
As disclosed in the patent to Donaldson, the gonadotropin hormones FSH and LH can be administered to the animal by intramuscular or subcutaneous injection in order to stimulate follicular development in the ovaries. Gonadotropin treatment is usually started between days 9 and 13 of the estrous cycle. Two or three days after administration of the gonadotropin hormones, prostaglandin F.sub.2.alpha. (or an analog), hereinafter referred to as PGF.sub.2.alpha. is injected in order to terminate the luteal phase of the estrous cycle prematurely by lysing the corpus luteum. Estrous occurs about two days after regression of the corpus luteum and lasts about half a day followed by ovulation with fertilization of the ovum occurring a few hours after ovulation.
Gonadotropin releasing hormone (GnRH) can also be administered in order to stimulate ovulation. For example, U.S. Pat. No. 5,180,711 to Hodgen discloses the administration of gonadotropin releasing hormone (GnRH) subsequent to the administration of a GnRH antagonist administered in an amount effective to initially suppress gonadotropin levels. The GnRH antagonist, specifically antide, and the GnRH can be controlled to achieve a desired suppression of endogenous gonadotropins levels over an extended time interval.