effect of early administration of equine chorionic gonadotropin and prostaglandin f2α on reproductive performance of postpartum dairy cows

the aim of this study was to evaluate the effect of ecg, pgf2α, and combination of ecg and pgf2α early postpartum on reproductive performance in high producing dairy cows. three hundred sixty eight postpartal holstein dairy cows were divided in 4 groups. cows in groups 1 and 2 received 500 iu ecg on day 8 ± 2 and cows in groups 3 and 4 received saline. cows in groups 1 and 3 received injections of 500 µg cloprostenol twice 8 hours apart between days 20 to 25 postpartum, and cows in group 2 and 4 received saline. presentation of a functional cl was assessed by ultrasonography of ovaries and serum progesterone concentration in groups 1 and 3. none of the treatments could improve fertility, and reproductive indices including 120 days in milk pregnancy rate, pregnancy loss, first service pregnancy rate and calving to conception interval was not different among the various different groups. only days to first service in ecg treated cows was marginally lower than that of control cows. treatment with ecg in cows in group 2 (ecg+saline) had no effect on the initiation of ovarian cyclical activity by day 30 ± 1 postpartum. resumption of ovarian cyclical activity by day 30 ±1 postpartum did not affect reproductive performance in dairy cows. additionally, treatment with ecg, pgf2α and combination of ecg and pgf2α had no effect on the prevalence of clinical endometritis, anovulatory anestrus, and follicular cyst. in conclusion, early treatment of high producing dairy cows after parturition with ecg and pgf2α had no effect on reproductive performance of lactating dairy cows.