Department of Surgery and Theriogenology, Faculty of Veterinary Medicine, University of Tripoli, Tripoli, Libya.
Department of Theriogenology, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt.
Open Vet J. 2024 Mar;14(3):822-829. doi: 10.5455/OVJ.2024.v14.i3.9. Epub 2024 Mar 31.
Reproductive efficiency affects dairy cow profitability. Ovarian function in postpartum (P.P.) has been better understood using ultrasound and hormonal assays. Optimizing ovulation synchronization and carefully timing artificial insemination (TAI) can greatly enhance reproductive rates in dairy cows.
This experiment was designed to investigate the reproductive performance and ovarian activity in early postpartum lactating dairy cows using the Presynch-PGF2α, Ovsynch protocol, and TAI.
Randomly the cows were assigned to a control group and a treatment group, based on the chronological order of their calving date. On day 14 P.P., both groups received two cloprostenol treatments, 14 days apart. Ultrasonographic inspections were conducted on day 14 to check ovarian activity and uterine contents. On day 11, after presynchronization, cows in the treatment group were given 100 µg IM. of cystorelin, followed by a luteolytic dose of 500 µg IM., cloprostenol on day 7, and a second dose of cystorelin on day 8 (36 hours later). After the second cystorelin injection by 16-20 hours, cows were inseminated, while the control group had all cows displaying spontaneous estrus between day 0 and day 28 were artificially inseminated.
Ovarian activity began to improve at 82.61% on day 19 P.P., with complete recovery between days 24 and 27 P.P. The second cloprostenol injection approached, causing follicular size to reach 8.41 ± 1.04 mm. After the second injection, ovarian activity switched from follicular to luteal, with corpus luteum rates of 23.91% and 26.1%. The presynchronized PGF2α regimen significantly enhanced ovarian activity from days 19-35 P.P. Ovulation and pregnancy rates in the Ovsynch group were 54.2% and 41.7% at the first timed artificial insemination (TAI), compared to 54.5% and 31.8% in the control group. There was no significant impact between them; it was just high in the presynchronized Ovsynch group. However, the P.P. period was minimized to 47-49 days till the first AI reached a 41.7% pregnancy rate and 20.8% at the second AI, for an overall 62.5%.
The current study concludes that presynchronization during preservice in clinically normal P.P. dairy cows reduces P.P. duration, increases ovarian activity performance, and reduces ovarian dysfunctions from day 19 to day 35 P.P., as well as improves the pregnancy rate.
繁殖效率会影响奶牛养殖的盈利能力。通过超声和激素检测，人们对产后（PP）的卵巢功能有了更好的了解。优化排卵同步并精确安排人工授精（TAI）可以极大地提高奶牛的繁殖率。
本实验旨在通过应用同期发情-PGF2α、Ovsynch 方案和 TAI 研究产后早期泌乳奶牛的繁殖性能和卵巢活动。
根据产犊日期的顺序，将奶牛随机分为对照组和治疗组。在产后 14 天（PP），两组均接受两次氯前列烯醇处理，间隔 14 天。在产后 14 天进行超声检查，以检查卵巢活动和子宫内容物。在预同步后的第 11 天，治疗组的奶牛肌肉注射 100μg 的 Cystorelin，然后肌肉注射 500μg 的黄体溶解剂量的氯前列烯醇，第 7 天，第 8 天（36 小时后）再注射一次 Cystorelin。第二次 Cystorelin 注射后 16-20 小时，对奶牛进行授精，而对照组所有自发发情的奶牛在第 0 天至第 28 天之间进行人工授精。
卵巢活动在产后 19 天开始改善，82.61%，在产后 24-27 天完全恢复。第二次氯前列烯醇注射接近时，卵泡大小达到 8.41±1.04mm。第二次注射后，卵巢活动从卵泡期转为黄体期，黄体率为 23.91%和 26.1%。同期发情的 PGF2α 方案显著增强了产后 19-35 天的卵巢活动。在第一次定时人工授精（TAI）时，Ovsynch 组的排卵和妊娠率分别为 54.2%和 41.7%，而对照组分别为 54.5%和 31.8%。两组之间没有显著影响，只是在同期发情的 Ovsynch 组较高。然而，通过第一次 AI 达到 41.7%的妊娠率和 20.8%的第二次 AI，将 P.P. 期最小化至 47-49 天，总妊娠率为 62.5%。
本研究表明，在临床正常的产后奶牛中进行同期发情预处理可以缩短产后时间，提高卵巢活动性能，减少从产后 19 天到 35 天的卵巢功能障碍，并提高妊娠率。
