책임운영기관 농촌진흥청 국립축산과학원 (로고)

We investigated the pregnancy rate after artificial insemination (AI) based on leakage of vulva mucus after artificially induced synchronized estrus in breeding Hanwoo cows. The study included 67 Hanwoo cows, and the experiment lasted about 4 months. Estrus synchronization for AI was achieved by administering a CIDR device along with GnRH (Gonadotrophin-releasing Hormone) for 7 days. The CIDR device was then removed, and PG (prostaglandin) was injected. Within 24 hours of PG injection, GnRH was administered for AI. First AI followed approximately 52 hours later, and second AI was conducted 14 hours after the first. Pregnancy rates were determined in relation to the presence or absence of mucus leakage, and the results were as follows: 46 cows showed mucus leakage during the estrus synchronization treatment, a rate of 68.7%, while 21 cows showed no mucus leakage, a rate of 31.3%. Pregnancy diagnosis was performed twice (at 28 days and approximately 90 days) using an early pregnancy diagnosis kit for the first diagnosis and a rectal, uterine palpation method for the second to confirm final pregnancy. Pregnancy rates according to mucus leakage were as follows: mucus visible at first AI, mucus visible at second AI (59.4%: 19/32); mucus visible at first AI, mucus invisible at second AI (50.0%: 2/4); mucus invisible at first AI, mucus invisible at second AI (64.7%: 11/17); and mucus visible at first AI, mucus invisible at second AI (59.4%: 10/14). The overall conception rate at 28 days was 62.7% (42/67 cows), and pregnancy rates at ~90 days after AI according to the presence or absence of mucus secretion were as follows: mucus visible at first AI, mucus visible at second AI (46.9%: 15/32 cows); mucus visible at first AI, mucus invisible at second AI (42.9%: 6/14 cows); mucus invisible at first AI, mucus visible at second AI (64.7%: 11/17 cows); and mucus invisible at first AI, mucus invisible at second AI (35.3%: 6/17 cows). This resulted in a final pregnancy rate of 43.3% (29/67 cows) and an estimated embryo mortality rate of 20.0% (13/65 cows). In conclusion, artificial insemination was effective at reducing the labor force, regardless of mucus leakage, when estrus was induced artificially for the production of synchronous calves on Hanwoo reproduction farms