Vallejo D A, Londoño J D, Yepes Y A, Tamayo V, Mejia A F, Maldonado J G
Department of Theriogenology, School of Veterinary Medicine, OHVRI Research Group, Faculty of Agrarian Sciences, University of Antioquia, Medellin, Colombia.
National Learning Service - SENA, Center of Renewable Natural Resources - La Salada, Research Group La Salada, Colombia Government, Caldas, Colombia.
Vet World. 2019 Nov;12(11):1779-1783. doi: 10.14202/vetworld.2019.1779-1783. Epub 2019 Nov 15.
This study aimed to evaluate the pregnancy rates in hair ewes using an Ovsynch synchronization protocol under a breeding system that combines fixed-time insemination plus a 10-day mating period as an alternative.
Through an experimental study (n=27), ewes were randomly located into one of three treatments: (1) Pre-synch (n=9): Prostaglandin F2α (PGF2α)+Gonadotropin-releasing hormone (GnRH)+PGF2α+GnRH; (2) Ovsynch (n=9): GnRH+PGF2α+GnRH; and (3) control: Ewes bred by natural mating (NM) (n=9). Ewes were fixed-time inseminated (fixed-time artificial insemination [FTAI]) with fresh semen, collected just before the insemination time through vaginoscopy at 16 h after the second GnRH (gonadorelin) injection. Each experimental group was placed separately during 15 days and, after this time, fertile rams were allowed back with ewes for a 10-day mating period. Control group ewes remained with the rest of the herd suitable for breeding and were bred under NM. Pregnancy diagnosis was performed by ultrasound at 28-, 56-, and 84-day post-breeding to differentiate between FTAI and NM pregnancies. Total (FTAI±NM) pregnancy rates at 56-day post-breeding were used to compared Pre-synch, Ovsynch, and control. For this purpose, two-tailed proportions comparison z-test was used with a 95% confidence level, for testing as the null hypothesis whether two proportions were equal.
Pregnancy rates were higher in control ewes (66.4%) than FTAI (46.6%). When pregnancy rates after a 10-day mating period (40%) were added, the final rate (86.6%) was significantly (p<0.05) higher in Ovsynch-based protocols. The pregnancy rate was significantly lower in FTAI ewes compared to FTAI +10-day mating group (p<0.05). The overall pregnancy rate was 88.0, 85.7, and 67.0 (p>0.05) for Pre-synch, Ovsynch, and control ewes, respectively.
These results provide evidence on the benefits of combined FTAI protocols for improving the reproductive efficiency of sheep.
本研究旨在评估在一种结合定时输精加10天交配期的繁殖系统下，使用Ovsynch同步方案对成年母羊妊娠率的影响，作为一种替代方法。
通过一项实验研究（n = 27），将母羊随机分为三种处理之一：（1）预同步组（n = 9）：前列腺素F2α（PGF2α）+促性腺激素释放激素（GnRH）+PGF2α+GnRH；（2）Ovsynch组（n = 9）：GnRH+PGF2α+GnRH；（3）对照组：自然交配（NM）的母羊（n = 9）。母羊在第二次GnRH（戈那瑞林）注射后16小时通过阴道镜检查在输精前采集新鲜精液进行定时输精（定时人工授精[FTAI]）。每个实验组分别放置15天，此后，让可育公羊与母羊一起进行10天的交配期。对照组母羊与其余适合繁殖的羊群一起饲养，并在自然交配下繁殖。在配种后28天、56天和84天通过超声进行妊娠诊断，以区分定时人工授精和自然交配的妊娠情况。使用配种后56天总的（定时人工授精±自然交配）妊娠率来比较预同步组、Ovsynch组和对照组。为此，使用双侧比例比较z检验，置信水平为95%，以检验两个比例是否相等作为零假设进行测试。
对照组母羊的妊娠率（66.4%）高于定时人工授精组（46.6%）。当加上10天交配期后的妊娠率（40%）时，基于Ovsynch方案的最终妊娠率（86.6%）显著更高（p<0.05）。定时人工授精母羊的妊娠率显著低于定时人工授精+10天交配组（p<0.05）。预同步组、Ovsynch组和对照组母羊的总体妊娠率分别为88.0%、85.7%和67.0%（p>0.05）。
这些结果为联合定时人工授精方案对提高绵羊繁殖效率的益处提供了证据。
