Effect of prostaglandin F۲α and GnRH administration at the time of artificial insemination on reproductive performance of dairy cows

The present study aimed to determine the effect of administrating prostaglandin F۲α (PGF۲α) and GnRH at the time of artificial insemination (AI) on the pregnancy per artificial insemination (P/AI) and the pregnancy survival rate of dairy cows. A number of ۸۳۰ lactating Holstein cows were randomly divided into four groups. Cows in group ۱ (n=۲۰۰) treated with ۱۵۰ µg d-cloprostenol. In group ۲ (n=۲۱۲), cows received ۱۰ µg buserelin acetate, and group ۳ (n=۲۰۵) was treated with both ۱۵۰ µg d-cloprostenol and ۱۰ µg buserelin acetate. In addition, ۲۱۳ cows were assigned as control group which received normal saline as placebo (group ۴). To measure progesterone, milk samples were collected at the insemination day and five days later. Pregnancy diagnosis was performed ۲۸ and ۶۰ days after the insemination, and the size and number of corpus luteum (CL) and twin pregnancies were recorded. Hormone therapies had no effect on the P/AI, pregnancy survival rate, and the size and number of CL. The P/AI ratio in groups ۱, ۲, ۳ and ۴ were ۳۸.۵۰%, ۴۲.۹۲%, ۴۱.۴۶% and ۴۰.۸۴%, and the pregnancy survival rates in groups ۱, ۲, ۳ and ۴ were ۸۴.۴۲%, ۸۶.۸۱%, ۸۸.۲۳% and ۸۳.۹۱%, respectively. The probability of a twin pregnancy was significantly higher in group ۱ (۱۵.۵۸%) than other groups. There was no significant difference between groups in terms of the offspring gender. In conclusion, the administration of d-cloprostenol or buserelin acetate at the time of AI had no effect on P/AI and pregnancy survival rate in dairy cattle under no heat stress condition, while the administration of d-cloprostenol increased the probability of twin pregnancies.

کلیدواژه ها:

Artificial insemination ، Buserelin ، Dairy cow ، D-Cloprostenol ، Pregnancy survival rate