Fate Of The Unfertilized Oocytes In Alpacas

Abstract

Fourteen mature female alpacas between three and six years of age were assigned to two experiments that were designed to determine the fate of unfertilized alpaca ova. In experiment one, 12 alpacas were given 50 ug of gonadotropin releasing hormone (GnRH) to induce ovulation. Ovulation was detected by transrectal ultrasonography (TUS). Alpacas were sacrificed, the oviducts and uterine horns were flushed and ova were identified under a stereo microscope. In experiment two, two alpacas having no dominant follicle, or corpus luteum, were given 400 IU of equine chorionic gonadotropin (eCG), monitored by TUS, and when the follicles reached 6 mm diameter, 75 ug of GnRH was given to induce ovulation. Animals were sacrificed seven days after ovulation induction and uterine horns were flushed. Results from experiment one show that at one day after ovulation, oocytes in the oviduct were of normal morphology and surrounded by cumulus oophorus cells. At two days after ovulation, the oocyte showed a clear, shrunken, dissociated cytoplasm as well as unequal cell division. At day three after ovulation, ova were surrounded by cumulus oophorus cells similar to those observed on day one after ovulation, as well a completely disorganized and clear cytoplasm. By day six after ovulation, ova were shrunken with broken zona pellucida. Results of experiment two show that all ova collected from the uterus were degenerated, but still surrounded by cumulus oophorus cells. In conclusion, unfertilized ova are not retained in the oviduct of the alpaca.