Li Ziyuan, Luan Shuyi, Yan LongGang, Xie Chengyun, Lian Zhengjie, Yang Mingmao, Mei Minmin, Lin Pengfei, Wang Aihua, Jin Yaping
College of Veterinary Medicine, Northwest A&F University, Yangling, China.
Key Laboratory of Animal Biotechnology, Ministry of Agriculture and Rural Affairs, Northwest A&F University, Yangling, China.
Front Vet Sci. 2024 Feb 1;11:1348734. doi: 10.3389/fvets.2024.1348734. eCollection 2024.
Optimizing the management of dairy cattle reproduction can reduce postpartum ovarian disease in high-yielding dairy cows and thus enhance ranch economic benefit. The hypothesis of this study was that the Double-Ovsynch (DO) protocol in high-producing dairy cows would result in a lower incidence of follicular cysts but a higher incidence of luteal cysts compared to those undergoing the Presynch-Ovsynch (PS) protocol.
In this experiment, 384 cows (204 primiparous and 180 multiparous) were allocated to the DO group, which followed the protocol: GnRH-7d-PGF2α-3d-GnRH-7d-Ovsynch-56 h (GnRH-7d-PGF2α-56 h-GnRH-16hTAI), starting on 39 ± 3 days in milk (DIM). Additionally, 359 cows (176 primiparous and 183 multiparous) were assigned to the PS group, which followed the protocol: PGF2α-14d-PGF2α-12d-Ovsynch-56 h, starting on 31 ± 3 DIM. In DO, B-mode ultrasound examinations were conducted 1 day after the GnRH-7d-PGF2α-3d-GnRH protocol to diagnose the presence of ovarian diseases followed by reexamination after 7 days of suspected cases. In PS, B-mode ultrasound examinations were conducted 1 day after the PGF2α-14d-PGF2α protocol to diagnose the presence of ovarian diseases followed by reexamination after 7 days. For all cows confirmed to having ovarian diseases, a second B-mode ultrasound examination was conducted at the time of the second GnRH and timed artificial insemination (TAI). If the ovary showed a normal developing follicle in combination with normal ovulation, the ovarian disease was considered to be cured.
The current study revealed no significant difference in the overall incidence and cure rate of postpartum ovarian diseases between DO and PS (incidence rate: 3.9% vs. 6.7%, cure rate: 50% vs. 41.7%, DO vs. PS). Also, there was no significant difference in the incidence and cure rate of luteal cysts between DO and PS (incidence rate: 2.9% vs. 2.2%, cure rate: 50.0% vs. 50.0%). The incidence of follicular cysts was significantly lower in the DO group than in the PS group (0.8% vs. 2.8%, DO vs. PS, = 0.037), but there was no significant difference in the cure rates (66.7% vs. 50%). The occurrence of inactive ovary was lower in DO compared to PS (0.2% vs. 1.7%, = 0.047). There was no significant difference in the pregnancy rate between the DO and PS groups (48.2% vs. 41.8%), although the DO group had a higher rate. What is different from our assumption is that PS did not effectively reduce the incidence of postpartum luteal cysts.
优化奶牛繁殖管理可降低高产奶牛产后卵巢疾病的发生率，从而提高牧场经济效益。本研究的假设是，与采用预同步-同期发情（PS）方案的高产奶牛相比，采用双同期发情（DO）方案的奶牛卵泡囊肿发生率较低，但黄体囊肿发生率较高。
在本实验中，384头奶牛（204头初产牛和180头经产牛）被分配到DO组，该组遵循的方案为：GnRH-7天-PGF2α-3天-GnRH-7天-同期发情-56小时（GnRH-7天-PGF2α-56小时-GnRH-16小时定时人工授精），从产犊后39±3天开始。此外，359头奶牛（176头初产牛和183头经产牛）被分配到PS组，该组遵循的方案为：PGF2α-14天-PGF2α-12天-同期发情-56小时，从产犊后31±3天开始。在DO组中，在GnRH-7天-PGF2α-3天-GnRH方案后的第1天进行B超检查以诊断卵巢疾病，疑似病例在7天后复查。在PS组中，在PGF2α-14天-PGF2α方案后的第1天进行B超检查以诊断卵巢疾病，7天后复查。对于所有确诊患有卵巢疾病的奶牛，在第二次GnRH和定时人工授精（TAI）时进行第二次B超检查。如果卵巢显示有正常发育的卵泡并伴有正常排卵，则认为卵巢疾病已治愈。
本研究表明，DO组和PS组产后卵巢疾病的总体发生率和治愈率无显著差异（发生率：3.9%对6.7%，治愈率：50%对41.7%，DO组对PS组）。DO组和PS组黄体囊肿的发生率和治愈率也无显著差异（发生率：2.9%对2.2%，治愈率：50.0%对50.0%）。DO组卵泡囊肿的发生率显著低于PS组（0.8%对2.8%，DO组对PS组，P = 0.037），但治愈率无显著差异（66.7%对50%）。DO组静止卵巢的发生率低于PS组（0.2%对1.7%，P = 0.047）。DO组和PS组的妊娠率无显著差异（48.2%对41.8%），尽管DO组的妊娠率较高。与我们的假设不同的是，PS组并未有效降低产后黄体囊肿的发生率。
