Bisinotto R S, Pansani M B, Castro L O, Narciso C D, Sinedino L D P, Martinez N, Carneiro P E, Thatcher W W, Santos J E P
Department of Animal Sciences, D.H. Barron Reproductive and Perinatal Biology Research Program, University of Florida, Gainesville, Florida, USA.
Department of Animal Sciences, D.H. Barron Reproductive and Perinatal Biology Research Program, University of Florida, Gainesville, Florida, USA.
Theriogenology. 2015 Jan 15;83(2):257-65. doi: 10.1016/j.theriogenology.2014.09.021. Epub 2014 Sep 19.
The objectives of this study were to determine the effects of supplemental progesterone on fertility responses of lactating dairy cows with a CL at the initiation of the timed artificial insemination (AI) program. Holstein cows were subjected to the Ovsynch protocol (Day -10 GnRH, Day -3 PGF2α, Day -0.7 GnRH, and Day 0 timed AI). Ovaries were scanned by ultrasonography on Day -10 and cows with CL were blocked by pen and assigned randomly to receive no supplemental progesterone (control, n = 863) or to receive a controlled internal drug-release (CIDR) insert containing progesterone from Days -10 to -3 (1CIDR, n = 862). Cows were observed for signs of estrus beginning on Day -9 based on removal of tail chalk and those in estrus received AI on the same day. Blood sampled from a subset of cows was analyzed for progesterone concentrations on Days -10, -9, -7, -5, -3, 0, 6, 13, and 19. Pregnancy was diagnosed on Days 32 and 60 after AI. Supplementation increased (P < 0.01) progesterone concentrations between Day -9 and -3 compared with control (7.5 vs. 6.2 ng/mL). Treatment had no effect on the ovulatory response to the first and final GnRH injections of the Ovsynch protocol, the proportion of cows that maintained their CL until the day of PGF2α injection, or the diameter of the ovulatory follicle before AI. Although the overall proportion of cows in estrus at AI did not differ between treatments, progesterone supplementation prevented (P < 0.01) cows from coming into estrus from Days -9 to -3 (0.0% vs. 4.7%), whereas it increased (P = 0.02) the proportion of cows inseminated in estrus from Days -2 to -1 (7.1% vs. 4.5%). Pregnancy per AI (P/AI) tended to be reduced (P = 0.06) by supplemental progesterone on Day 32 (40.5% vs. 45.0%), but not on Day 60 after AI (36.6% vs. 39.7%). A tendency for an interaction (P = 0.09) between treatment and the presence of CL at the PGF2α injection was observed for P/AI on Day 32 in cows that received timed AI because progesterone supplementation reduced P/AI in cows that maintained their CL until Day -3 (40.3% vs. 46.7%); however, it increased P/AI in those that did not have a CL at PGF2α (38.1% vs. 27.7%). Treatment did not affect pregnancy loss between Days 32 and 60 of gestation. In conclusion, incorporating a single intravaginal insert to the timed AI program increased progesterone concentrations in plasma by 1.3 ng/mL, but did not benefit fertility in dairy cows that have CL at the initiation of the synchronization protocol.
本研究的目的是确定在定时人工授精（AI）程序开始时，补充孕酮对具有黄体（CL）的泌乳奶牛繁殖反应的影响。荷斯坦奶牛接受Ovsynch方案（第-10天注射促性腺激素释放激素（GnRH），第-3天注射前列腺素F2α（PGF2α），第-0.7天注射GnRH，第0天定时AI）。在第-10天通过超声检查卵巢，将有CL的奶牛按栏进行分组，并随机分配至不补充孕酮组（对照组，n = 863）或从第-10天至第-3天接受含孕酮的控制内部药物释放（CIDR）装置组（1CIDR组，n = 862）。从第-9天开始观察奶牛的发情迹象，根据尾粉笔的去除情况判断，处于发情期的奶牛在同一天接受AI。在第-10、-9、-7、-5、-3、0、6、13和19天对一部分奶牛采集血样分析孕酮浓度。在AI后第32天和第60天诊断妊娠。与对照组相比，补充孕酮使第-9天至第-3天的孕酮浓度升高（P < 0.01）（7.5对6.2 ng/mL）。处理对Ovsynch方案中第一次和最后一次GnRH注射的排卵反应、在PGF2α注射日之前维持CL的奶牛比例或AI前排卵卵泡直径没有影响。虽然处理之间在AI时处于发情期的奶牛总体比例没有差异，但补充孕酮可防止（P < 0.01）奶牛在第-9天至第-3天发情（0.0%对4.7%），而在第-2天至第-1天增加了（P = 0.02）处于发情期接受授精的奶牛比例（7.1%对4.5%）。AI后的妊娠率（P/AI）在第32天有因补充孕酮而降低的趋势（P = 0.06）（40.5%对45.0%），但在AI后第60天没有（36.6%对39.7%）。在接受定时AI的奶牛中，观察到处理与PGF2α注射时CL的存在之间在第32天的P/AI有交互作用趋势（P = 0.09），因为补充孕酮使CL维持到第-3天的奶牛的P/AI降低（40.3%对46.7%）；然而，在PGF2α时没有CL的奶牛中P/AI增加（38.1%对27.7%）。处理不影响妊娠第32天至60天之间的妊娠丢失。总之，在定时AI程序中加入单个阴道装置可使血浆孕酮浓度升高1.3 ng/mL，但对同步方案开始时具有CL的奶牛的繁殖力没有益处。
