Abstract：
Two experiments were conducted to compare, follicle diameter (FD) on Day -1, corpus luteum (CL) area on Day 7, progesterone (P4) concentration on Day 7 and 18, pregnancy per timed artificial insemination (TAI) on Day 30, and pregnancy loss (PL) between Days 30 and 60 after TAI (TAI, Day 0) using two different synchronization protocols. In Experiment 1, Angus cows (n = 1148) were randomly assigned to either 7-d progesterone CO-Synch (7-d CO-Synch) or 8-d progesterone + estradiol (8-d P + ES) synchronization protocols for TAI. On Day -10, cows in the 7-d CO-Synch treatment group (n = 574) received a progesterone-releasing intravaginal device (PIVD; 0.5 g P4) and GnRH (0.105 mg), on Day -3 the PIVD was removed and cows received cloprostenol (0.150 mg), then, on Day 0 (64 h after PIVD removal), cows received GnRH (0.105 mg) and were TAI. On Day -10, cows in the 8-d P + ES treatment group (n = 574) received a PIVD (0.5 g P4) and estradiol benzoate (2.0 mg), on Day -2 the PIVD was removed, and cows received cloprostenol (0.150 mg) and estradiol cypionate (0.5 mg), then, on Day 0 (48 h after PIVD removal), cows were TAI. Pregnancy per TAI was determined on Days 30 and 60. In a subset of cows (7-d CO-Synch, n = 41; 8-d P + ES, n = 40), serum P4 concentration was evaluated on Day 18. In Experiment 2, anestrus (n = 34) and cyclic (n = 34) suckled beef cows were selected and submitted at random on Day -10, to either 7-d CO-Synch or 8-d P + ES treatment groups. Follicle diameter on Day -1, CL area, and serum P4 concentration on Day 7 were determined. In Experiment 1, pregnancy per TAI on Day 30 did not differ (7-d CO-Synch = 48.9%; 8-d P + ES = 45.6%) between treatments but it was greater for cows with BCS ≥5 (P < 0.01). Pregnancy loss between Days 30 and 60 did not differ between treatment groups but tended to be greater in cows with BCS <5.0 (P < 0.1). In a subset of cows, serum P4 concentration on Day 18 did not differ between treatment groups but tended to be lower (P < 0.1) in cows that had PL between Days 30 and 60 compared to cows that had no PL. In Experiment 2, FD tended to be greater (P < 0.1) and CL area was greater (P = 0.05) in anestrus cows from 7-d CO-Synch treatment. In cyclic cows, the treatment did not affect the FD or CL area. In conclusion, there was no difference in pregnancy per TAI on Day 30 and PL between Days 30 and 60 between cows using 7-d CO-Synch + PIVD or 8-d estradiol-based + PIVD protocols for estrus synchronization and TAI.
摘要：
进行了两个实验比较，第-1天的卵泡直径（FD），第7天的黄体（CL）面积，第7天和第18天的孕酮（P4）浓度，第30天的每次定时人工授精（TAI）和妊娠损失（PL）在TAI后30天至60天（TAI，第0天)使用两种不同的同步协议。在实验1中，将安格斯母牛（n=1148）随机分配到7d孕酮CO-Synch（7dCO-Synch）或8d孕酮雌二醇（8dPES）同步方案中TAI。在第-10天，7天CO-Synch治疗组（n=574）的奶牛接受了孕酮释放阴道内装置（PIVD；0.5gP4）和GnRH（0.105mg），在第-3天，PIVD被去除，奶牛接受氯前列醇（0.150毫克），然后,在第0天（PIVD去除后64小时），奶牛接受GnRH(0.105mg)和TAI。在第-10天，8天P+ES处理组（n=574）的奶牛接受PIVD（0.5gP4）和苯甲酸雌二醇（2.0mg），在第2天，PIVD被移除，母牛接受了氯前列醇（0.150毫克）和环戊酸雌二醇（0.5毫克），然后,在第0天（PIVD去除后48小时），奶牛是TAI。在第30天和第60天确定每个TAI的妊娠。在一部分奶牛中(7-d共同步，n=41；8-dP+ES，n=40),在第18天评估血清P4浓度。在实验2中，选择了发情期（n=34）和循环（n=34）的乳牛，并在第-10天随机接受7dCO-Synch或8dPES处理组。第-1天的卵泡直径，CL面积，测定第7天的血清P4浓度。在实验1中，第30天每个TAI的妊娠率在处理之间没有差异（7-dCO-Synch=48.9％；8-dPES=45.6％），但对于BCS≥5的母牛则更大（P<0.01）。第30天和第60天之间的妊娠损失在处理组之间没有差异,但在BCS<5.0(P<0.1)的母牛中倾向于更大。在一部分奶牛中，第18天的血清P4浓度在处理组之间没有差异,但是与没有PL的母牛相比,在第30天和第60天之间具有PL的母牛中趋于更低(P<0.1)。在实验2中，在7天CO-Synch处理的发情期母牛中，FD倾向于更大（P<0.1），CL面积更大（P=0.05）。在循环奶牛中，治疗未影响FD或CL区.总之,使用7dCO-SynchPIVD或8d基于雌二醇的PIVD方案进行发情同步和TAI，在第30天和第30天至第60天之间，每个TAI的妊娠率没有差异。
