무발정 증상을 보이는 젖소 65두를 대상으로 몇 가지 호르몬 처리기법을 사용하여 소의 번식효율 향상시키고자 본 실험을 수행하였다. Group 1. Ovsynch program (GnRH-PGF$_2$ a /PGF$_2$ a/GnRH), Group 2. Two plus Two program (GnRH-PGF$_2$ a /PGF$_2$ a/GnRH), Group 3. progesterone implant (CIDR)-GnRH/PGF$_2$ a/PGF$_2$ a/GnRH과 Group 4. (Follicular rupture-progesterone implant-GnRH/ PGF$_2$ a/PGF$_2$ a/GnRH)로 구분하고 최종 GnRH 처지 후 발정 유도율, 발정유도시간, 임신율, 유산율, 인공수정 후 60일까지의 임신율을 조사하여 다음과 같은 결론을 얻었다. 1. 발정 유도율은 Group 1, 2, 3에서는 각기67%, 75%, 70%로서 비슷하게 나타났으나, Group 4에서는 86%로서 유의적(P＜0.05)으로 높은 발정율을 나타내었다. 2. 발정 유도 시간은 progesterone implant를 사용한 Group 3과 Group 4는 각각 24, 23시간으로 발정유도 시간을 단축시키는데 효과가 있었다. 3. 각 호르몬 투여 임신율은 progesterone implant를 사용한 Group 3과 Group 4가 75%, 85%로서 사용하지 않은 Group 1과 Group 2보다 유의적(P<0.05)으로 높은 임신율을 나타내었다. 4. 임신 49일까지의 유산율은 Group 4가 5.9%로 낮은 유산율을 보였다. 이상의 실험결과를 종합하면 무발정우에서 각종 호르몬을 투여하기 전에 난소를 확인하여 폐쇄 난포가 있는 것은 폐쇄난포를 제거하고 progesterone implant 제제인 CIDR를 질내에 장착하는 것이 무발정우의 발정유기 및 수태율 향상에 효과적이라고 사료된다.
The objective of this study was to compare the effect of four different estrus induction methods in anestrus cows on the estrus induction and pregnancy following artificial insemination (AI). Sixty-five cows (3∼4 years old) were selected and divided into four different estrus induction treatment groups. Group 1, 12 cows were treated by Ovsynch program combined with GnRH and PGF$_2$a. Group 2, 12 cows were treated by "Tow plus Two" program with GnRH and PGF$_2$a. Group 3, 20 cows were treated by "Tow plus Two" program following intravaginal progesterone implantation (CIDR). Twenty one cows in Group 4 were treated by "Tow plus Two" program following follicular rupture and intravaginal progesterone implantation. Cows were then observed estrus induction and inseminated artificially at 12 h and 24 h after standing estrus. The rates of estrus induction in Group 4 (18/21, 86%) was significantly (P<0.05) higher than those in groups 1, 2 and 3 (8/12, 67%; 9/12, 75%; 14/20, 70%). In the mean time of onset of estrus after final administration of GnRH in different hormone-treated cows, the cows in Group 3 (24.2$pm$2.2) and Group 4 (23.4$pm$2.0) were significantly (P<0.05) shorter than that in Group 1 (28.5$pm$4.6) and Group 2 (26.4$pm$3.3). The rates of pregnancy diagnosed on Day 28 were significantly different between treatment groups. Significantly (P<0.05) higher rate of pregnancy was observed in Group 4 (17/20, 85.0%) than those in Groups 1, 2 and 3 (7/11, 63.6%; 8/12, 66.7%; 15/20, 75.0%, respectetively). The rate of abortion diagnosed on 49 days of gestation was significantly (P<0/05) lower in Group 4 (1/17, 5.9%) than those in Groups 1, 2 and 3 (2/7, 28.7%; 2/8, 25% and 3/15, 20%, respectively). In conclusion, combined treatments with GnRH and PGF$_2$a following follicular rupture and progesterone implant in anestrus cows was considered to be most effective in estrus induction and maintenance of pregnancy. Further studies are needed to verify the functional mechanisms of residual follicles in anestrus ovaries on retarding the response of hormonal treatments.sponse of hormonal treatments.
