بررسي تاثير تزريق hCG در روز پنجم پس از تلقيح مصنوعي بر افزايش اعتبار عيار سرمي پروژسترون و بهبود ميزان باروري گاوهاي هلشتاين

A study on the possible effects of administration of human chorionic gonadotropin, at 5th day after AI to improve conception rate and serum progesterone concentration in Holstein dairy cattle

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 cows.39 lactating dairy cattle randomly allotted to 2 experimental groups: Treated group included 19 dairy cows that received 3000IU hCG on day 5 after AI and non treated (control) group included 21 dairy cows that only received 5ml normal saline 5 day after AI. Blood sampling obtained on day 5, before administration of exogenous hCG and normal saline, and also on day 13 after AI to measure serum progesterone concentrations. Pregnancy diagnosis was performed by rectal palpation 40- 60 days after AI. On day 13 average serum progesterone concentrations were 7.72ng/ml and 8.25ng/ml in hCG and control groups respectively. Pregnancy proportion in hCG and control groups were 31.6% and 47.6% respectively. Statistical analysis of results did not show any significant difference between two groups in respect to pregnancy proportion or progesterone concentrations (p>0.05).