• Journal of Embryo Transfer
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• v.18 no.2
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• pp.115-124
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• 2003

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.

• Korean Journal of Veterinary Research
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• v.35 no.3
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• pp.603-613
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• 1995

Plasma progesterone($P_4$) assay has been introduced to apply to the differential diagnosis of reproductive disorders and the monitoring of responses of ovarian dysfunction to $PGF_2{\alpha}$ or GnRH treatment in the 204 postpartum and postinsemination subestrus dairy cows. 1. The incidence rate of reproductive disorders in 204 subestrus cows, diagnosed by palpation per rectum and plasma $P_4$ determination using 'Two sample test'(Day 0+Day 10) were as follows; silent heat or error of estrus detection 110(53.9%), persistent corpus luteum 26(12.7%), follicular cyst 16(7.8%), inactive ovary 12(5.9%), luteal cyst 11(5.4%), granulosa cell tumor of ovary 1(0.5%), fetal mummification 1(0.5%), endometritis 15(7.4%) and pyometra 12(5.9%), respectively. 2. After the $PGF_2{\alpha}$ treatment to the 76 cows with silent heat or error of estrus detection, persistent corpus luteum, or luteal cyst, plasma $P_4$ concentrations at day 3 post treatment using 'Two sample test'(Day 0+Day 3) remained low(<1.0ng/ml) in all 76 cows. Therefore all 76 cows responded positively to $PGF_2{\alpha}$ treatment. Seventeen cows with follicular cyst or inactive ovary were treated with GnRH. All 7 cows with follicular cyst and 4 cows with inactive ovary remained high($${\geq_-}1.0ng/ml$$) a plasma $P_4$ concentrations at day 12 post treatment using 'Two sample test'(Day 0+Day 12), but 6 cows with inactive ovary remained low(<1.0ng/ml) a plasma $P_4$ concentrations. Therefore all 7 cows with follicular cyst and 4 cows with inactive ovary responded positively, but 6 cows with inactive ovary responded negatively to GnRH treatment. 3. The mean days from treatment to first service, number of cows conceived on first service(%), mean number of services per conception, mean days from initial treatment to conception, and mean number of cows conceived by 100 days post treatment(%) were 5.0 and 26.2 days, 45(59.2%) and 6(35.3%) cows, 1.5 and 1.7 services, 13.6 and 22.6 days, and 62(81.6%) and 9(52.9%) cows in group of $PGF_2{\alpha}$ and GnRH treatment, respectively. These results indicated that plasma $P_4$ assay was practical as an aid to diagnosing reproductive disorders and to monitoring responses of ovarian dysfunction to $PGF_2{\alpha}$ and GnRH treatment in subestrus cows.