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

The objective of this trial was to determine the efficacy of the progestero ne removal inserted device (PRID) and PGF(2 alpha) analogue treatments comb ined with hCG administration on fertility in transitional mares. A total of forty-five thoroughbred mares were used in this experiment. Anim als were divided into three groups. Progesterone-impregnated vaginal device s (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-clop rostenol (0.075 mg) was intramuscularly injected two times at a 14-day inte rval in the second group (n = 15). Two milliliters of serum physiologic wer e intramuscularly injected two times at a 14-day interval in the third grou p (Control, n = 15). After injections and removal of progesterone-impregnat ed vaginal devices (PRID), the oestrous cycle of each mare was followed thr ough teasing, palpation per rectum and transrectal ultrasonography. After t he detection of oestrous, hCG (3000 IU) was intravenously injected to the m ares of the first and second groups on the 4(th) day of oestrus. Follicles were monitored every 12 hours with ultrasonography until the ovulation occu rred. Mares were mated naturally every other day beginning from 84 hours af ter detection of estrous until the end of estrous. Pregnant mares were dete rmined with ultrasonography on day 20 after the last mating. There was a st atistical significant difference (P < 0.05) between groups I and III and al so 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 cho rionic gonadotropin and PGF(2<alpha>) combined with human chorionic gonadot ropin applications were effective to induce oestrous and ovulation in trans itional mares.