Oestrous synchronization with progesterone impregnated device and prostaglandin F-2 alpha both combined with human chorionic gonadotropin in transitional mares

Abstract

The objective of this trial was to determine the efficacy of the progesterone removal inserted device (PRID) and PGF(2 alpha) analogue treatments combined with hCG administration on fertility in transitional mares. A total of forty-five thoroughbred mares were used in this experiment. Animals were divided into three groups. Progesterone-impregnated vaginal devices (PRID) were inserted into anterior vagina of the mares of the first group (n = 15). The devices were replaced on day 7 and removed on day 14. D-cloprostenol (0.075 mg) was intramuscularly injected two times at a 14-day interval in the second group (n = 15). Two milliliters of serum physiologic were intramuscularly injected two times at a 14-day interval in the third group (Control, n = 15). After injections and removal of progesterone-impregnated vaginal devices (PRID), the oestrous cycle of each mare was followed through teasing, palpation per rectum and transrectal ultrasonography. After the detection of oestrous, hCG (3000 IU) was intravenously injected to the mares of the first and second groups on the 4(th) day of oestrus. Follicles were monitored every 12 hours with ultrasonography until the ovulation occurred. Mares were mated naturally every other day beginning from 84 hours after detection of estrous until the end of estrous. Pregnant mares were determined with ultrasonography on day 20 after the last mating. There was a statistical significant difference (P < 0.05) between groups I and III and also II and III, for the oestrus, ovulation, pregnancy rates, ovulation time, oestrus duration and mating number required per conception, respectively. In conclusion, both progesterone impregnated device combined with human chorionic gonadotropin and PGF(2) combined with human chorionic gonadotropin applications were effective to induce oestrous and ovulation in transitional mares.