earticle

영어

The objectives of this study were to determine the effect of administration of exogenous hCG 5 days after artificial insemination (AI) on serum progesterone concentration and conception rate in dairy cattle. In this experiment 5 days after AI the cows were alternately assigned randomly to treatment group (n=67) received an injection of 1,500 IU hCG (Chorulon) and control group (n=61), received no treatment. On day 5, 10, 15 and 20 blood samples from 8 of cows (4 in each group) were obtained to measure serum progesterone concentration. Cows that were detected in estrous after days 18~24 were reinseminated and recorded as no pregnant (open) to the prior AI. The uteri of cows not observed in estrous were palpated per rectum 60 days after insemination to determine pregnancy status. And pregnancy was diagnosed by ultrasonic examination. Pregnancy proportion in treatment and control groups were 52.5 and 36.1%, respectively. The results demonstrated that there was no significant differences between two groups (p=0.0568). Mean serum progesterone concentrations did not differ between treatment and control groups on day 5 (0.377 versus 0.375 ng/mL). On day 20 serum progesterone concentrations were greater in the treatment group compared with control group (3.085 versus 2.010 ng/mL). In conclusion, 1,500 IU of hCG 5days after insemination did improve pregnancy rate in dairy cattle, moreover the fact that serum progesterone concentration were higher in treatment group.