Teagasc, Animal and Grassland Research and Innovation Centre, Moorepark, Fermoy, Co. Cork, Ireland.
J Dairy Sci. 2013 Mar;96(3):1485-98. doi: 10.3168/jds.2011-5250. Epub 2013 Jan 16.
Logistic regression was used to identify factors associated with fertility outcomes in cows treated with protocols to synchronize estrus and ovulation. Lactating dairy cows (n=1,538) were enrolled in a completely randomized block design study to evaluate synchronization treatments. Within each herd (n=8), cows were divided into 3 calving groups: early [≥ 42 d in milk (DIM) at mating start date (MSD); n=1,244], mid (21 to 41 DIM at MSD; n=179), and late (0 to 20 DIM at MSD; n=115), based on DIM at MSD. Cows in the early-, mid-, and late-calving groups were synchronized to facilitate estrus or timed artificial insemination (TAI) at MSD (planned breeding 1; PB1), 21 d (PB2), and 42 d (PB3) after MSD, respectively. For each PB, cows in the relevant calving group were stratified by parity and calving date and randomly assigned to (1) d -10 GnRH (10 μg i.m. of buserelin) and CIDR [controlled internal drug release insert, 1.38 g of progesterone (P4)]; d -3 PGF(2α) (25mg i.m. of dinoprost); d -2 CIDR out and AI at observed estrus (CIDR_OBS); (2) same as CIDR_OBS, but GnRH 36 h after CIDR out and TAI 18 h later (CIDR_TAI); (3) same as CIDR_TAI, but no CIDR (i.e., Ovsynch); or (4) untreated controls (CTRL). Use of a CIDR-based ovulation synchronization protocol (i.e., CIDR_TAI) increased synchronization rates in anovular cows. Both CIDR_OBS and CIDR_TAI animals without a corpus luteum (CL) had increased likelihood of conception at first service compared with Ovsynch animals without a CL. Animals with low body condition score (BCS) treated with CIDR_OBS had an increased likelihood of conceiving at first service compared with low-BCS animals treated with CIDR_TAI, Ovsynch, or CTRL. Animals <60 d in milk (DIM) treated with CIDR_OBS and CIDR_TAI had increased likelihood of conceiving at first service compared with animals treated with Ovsynch. Treatment with CIDR_TAI increased synchronization rate in cows categorized as low BCS, anovulatory, and <60 DIM compared with both CIDR_OBS and Ovsynch, and increased submission rate compared with CIDR_OBS. Conception rate in cows within these categories, however, was greatest for CIDR_OBS, resulting in minimal differences in actual pregnancy rates between CIDR_OBS and CIDR_TAI treatments, both of which were superior to Ovsynch. Treatment differences in the response variables investigated were minimal in cows categorized as medium or high BCS, ovulatory, and >60 DIM, indicating that CIDR-based protocols could be targeted at particular cows, and all other cows could be synchronized using Ovsynch.
采用逻辑回归分析方法，对采用同期发情和排卵方案治疗的奶牛的生育结果相关因素进行了识别。在一项完全随机分组设计的研究中，纳入了泌乳奶牛（n=1538），以评估同步处理。在每个牛群内（n=8），根据配种开始日期（MSD）时的产奶天数（DIM），将奶牛分为 3 个产犊组：早（≥42 DIM；n=1244）、中（21 至 41 DIM；n=179）和晚（0 至 20 DIM；n=115）。根据 MSD 时的 DIM，早、中、晚产犊组的奶牛被同步发情或定时人工授精（TAI），分别在 MSD 时（计划配种 1；PB1）、21 天（PB2）和 42 天（PB3）后进行。对于每个 PB，根据胎次和产犊日期，相关产犊组的奶牛被分层，并随机分配到（1）d-10 GnRH（10 μg 肌肉注射的布舍瑞林）和 CIDR[控释内部药物释放插入物，1.38 g 孕酮（P4）]；d-3 PGF2α（25mg 肌肉注射地诺前列酮）；d-2 取出 CIDR 并在观察到的发情时进行 AI（CIDR_OBS）；（2）与 CIDR_OBS 相同，但在取出 CIDR 后 36 小时给予 GnRH，并在 18 小时后进行 TAI（CIDR_TAI）；（3）与 CIDR_TAI 相同，但不使用 CIDR（即 Ovsynch）；或（4）未处理的对照组（CTRL）。使用基于 CIDR 的排卵同步方案（即 CIDR_TAI）可提高无黄体奶牛的同步率。CIDR_OBS 和 CIDR_TAI 动物无黄体（CL）时首次配种的受孕可能性增加，而无 CL 的 Ovsynch 动物则没有。与接受 CIDR_TAI 治疗的低体况评分（BCS）动物相比，接受 CIDR_OBS 治疗的低 BCS 动物首次配种的受孕可能性增加。与接受 CIDR_TAI、Ovsynch 或 CTRL 治疗的低 BCS 动物相比，接受 CIDR_OBS 治疗的<60 DIM 的动物首次配种的受孕可能性增加。与接受 Ovsynch 治疗的动物相比，接受 CIDR_OBS 和 CIDR_TAI 治疗的<60 DIM 的动物首次配种的受孕可能性增加。与 CIDR_OBS 和 Ovsynch 相比，CIDR_TAI 治疗可提高低 BCS、无黄体和<60 DIM 奶牛的同步率，并提高提交率。然而，这些类别中的奶牛的受孕率以 CIDR_OBS 最高，导致 CIDR_OBS 和 CIDR_TAI 治疗之间的实际妊娠率差异最小，这两种治疗均优于 Ovsynch。在中等或高 BCS、排卵和>60 DIM 的奶牛中，对所研究的反应变量的治疗差异最小，表明基于 CIDR 的方案可以针对特定的奶牛，所有其他奶牛都可以使用 Ovsynch 进行同步。
