Department of Animal Science, Cornell University, Ithaca, NY 14853.
Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison 53706.
J Dairy Sci. 2021 Oct;104(10):11210-11225. doi: 10.3168/jds.2021-20190. Epub 2021 Jul 23.
Our primary objective was to evaluate the effect of feeding rumen-protected Met (RPM) in the pre- and postpartum total mixed ration (TMR) on pregnancy per artificial insemination (AI) and pregnancy loss in multiparous Holstein cows. We also evaluated multiple secondary reproductive physiological outcomes before and after AI, including uterine health, ovarian cyclicity, response to synchronization of ovulation, and markers of embryo development and size. A total of 470 multiparous Holstein cows [235 at the University of Wisconsin (UW) and 235 at Cornell University (CU)] were used for this experiment. Experimental treatment diets were applied at the pen level (2 and 4 close-up pens at CU and UW, respectively, and 12 and 6 postfresh pens at CU and UW, respectively); thus, pen was the experimental unit, and cow was the observational unit. Cows were enrolled and randomly assigned to be fed the experimental treatment diets at approximately 4 wk before parturition until 67 d of gestation [147 d in milk (DIM)] after their first service. Close-up dry cow and replicated lactation pens were randomly assigned to treatment diets: RPM, prepartum = 2.83% (UW) and 2.85% (CU), postpartum = 2.58% (UW) and 2.65% (CU); and control (CON), prepartum = 2.30% (UW) and 2.22% (CU), postpartum = 2.09% (UW) and 2.19% (CU; Met as percentage of metabolizable protein). Vaginal discharge and uterine cytology (percentage of polymorphonuclear leucocytes) were evaluated at 35 ± 3 DIM. Cows received timed AI (TAI) at 80 ± 3 DIM after synchronization of ovulation with the Double-Ovsynch protocol. Ovarian cyclicity status, response to synchronization of ovulation, and luteal function were determined by measuring circulating concentrations of progesterone at 35 and 49 ± 3 DIM, 48 and 24 h before TAI, and 8, 18, 22, 25, and 29 d after TAI. Interferon-stimulated gene expression in white blood cells were compared on 18 d after TAI (CU only) and pregnancy-specific protein B concentrations at 22, 25, 29, 32, and 67 d after TAI. Pregnancy status was determined using pregnancy-specific protein B at 25 and 29 d after TAI, and by transrectal ultrasonography at 32, 39, and 67 d after TAI. Embryo and amniotic vesicle size were determined at 32 and 39 d after TAI. Pregnancy per AI (25 d: 64.7 vs. 64.0%, 32 d: 54.3 vs. 55.1% for CON and RPM, respectively) and pregnancy loss (25 to 67 d: 22.6 vs. 19.2% for CON and RPM, respectively) for synchronized cows did not differ. The proportion of cows with purulent vaginal discharge (CON = 7.7 vs. RPM = 4.6%) and cytological endometritis (CON = 20.8 vs. RPM = 23.6%) did not differ. Cyclicity status, ovarian responses to the synchronization protocol, and synchronization rate also did not differ. In addition, fold change for interferon-stimulated genes, concentrations of pregnancy-specific protein B, and embryo size were not affected by treatments. In conclusion, feeding RPM in the pre- and postpartum TMR at the amounts used in this experiment did not affect uterine health, cyclicity, embryo development, or reproductive efficiency in dairy cows.
我们的主要目标是评估在围产期总混合日粮（TMR）中添加瘤胃保护型蛋氨酸（RPM）对经人工授精（AI）受孕的荷斯坦奶牛妊娠率和妊娠损失的影响。我们还评估了 AI 前后多个次要生殖生理指标，包括子宫健康、卵巢周期性、排卵同步反应以及胚胎发育和大小的标志物。共有 470 头经产荷斯坦奶牛[威斯康星大学（UW）235 头，康奈尔大学（CU）235 头]参与了这项实验。实验处理日粮在畜栏水平上应用（CU 和 UW 分别有 2 和 4 个接近畜栏和 12 和 6 个产后畜栏）；因此，畜栏是实验单位，奶牛是观察单位。奶牛在分娩前约 4 周被招募并随机分配到实验处理日粮中，直到第一次服务后 67 天的妊娠（147 天泌乳）[产后第 147 天]。接近干奶牛和重复泌乳畜栏被随机分配到处理日粮：RPM，围产期=2.83%（UW）和 2.85%（CU），产后=2.58%（UW）和 2.65%（CU）；和对照（CON），围产期=2.30%（UW）和 2.22%（CU），产后=2.09%（UW）和 2.19%（CU；蛋氨酸作为可代谢蛋白的百分比）。在 35 ± 3 DIM 时评估阴道分泌物和子宫细胞学（多形核白细胞的百分比）。在排卵同步用双-Ovsynch 方案后，奶牛在 80 ± 3 DIM 时接受定时 AI（TAI）。通过在 35 和 49 ± 3 DIM、排卵同步前 48 和 24 小时、TAI 后 8、18、22、25 和 29 天测量循环孕酮浓度来确定卵巢周期性状态、排卵同步反应和黄体功能。仅在 CU 上比较 TAI 后 18 天的干扰素刺激基因表达和妊娠特异性蛋白 B 浓度，以及 TAI 后 22、25、29、32 和 67 天的妊娠特异性蛋白 B 浓度。在 TAI 后 25 和 29 天使用妊娠特异性蛋白 B 以及在 TAI 后 32、39 和 67 天进行经直肠超声检查来确定妊娠状态。在 TAI 后 32 和 39 天确定胚胎和羊膜囊的大小。同步牛的妊娠率（25 天：64.7%比 64.0%，32 天：54.3%比 55.1%，CON 和 RPM）和妊娠损失（25 至 67 天：22.6%比 19.2%，CON 和 RPM）没有差异。化脓性阴道分泌物（CON=7.7%比 RPM=4.6%）和细胞学子宫内膜炎（CON=20.8%比 RPM=23.6%）的奶牛比例没有差异。周期性状态、卵巢对同步方案的反应和同步率也没有差异。此外，干扰素刺激基因、妊娠特异性蛋白 B 浓度和胚胎大小的倍数变化不受处理的影响。总之，在本实验中使用的围产期 TMR 中添加 RPM 不会影响奶牛的子宫健康、周期性、胚胎发育或繁殖效率。
