North Florida Research and Education Center, Marianna, FL.
University of Nebraska West Central Research and Extension Center, North Platte, NE.
J Anim Sci. 2018 Apr 14;96(4):1388-1395. doi: 10.1093/jas/sky059.
Two experiments were conducted to evaluate the effects of a high concentrate, s.c. PGF2α compared with a conventionally concentrated, i.m. PGF2α in estrus synchronization protocols for heifers. In Exp. 1, 869 Angus-based beef heifers were enrolled at 8 locations. All heifers were exposed to the 7-d CO-Synch + controlled internal drug release (CIDR) estrus synchronization protocol. On day 7 of the protocol heifers received 100 µg of GnRH i.m., and a CIDR insert for 7 d. On day 0, at CIDR removal, estrous detection patches were applied to heifers and, within location, heifers randomly received 1 of 2 PGF2α treatments: 5 mL of Lutalyse i.m. (CONTROL; n = 434) or a 2 mL of Lutalyse HighCon s.c. (HiCON; n = 435). A second GnRH injection was administered at 54 ± 2 h and heifers were fixed-time AI (TAI). Heifers were evaluated for estrous activity at TAI by determining the activation of estrous detection patches. Pregnancy rates to AI (PR/AI) were diagnosed by transrectal ultrasonography between 35 and 55 d after TAI. The percentage of heifers exhibiting estrus between day 0 and TAI did not differ (P = 0.68) between CONTROL and HiCON treatments (47 vs. 46 ± 4%, respectively). Additionally, PR/AI were similar (P = 0.65) between CONTROL and HiCON treatments (46 vs. 45 ± 3%). In Exp. 2, 190 Angus-based beef heifers were enrolled at 2 locations. Heifers were exposed to the melengestrol acetate (MGA)-PGF2α protocol where they were offered 0.5 mg MGA per day from days 1 to 14. On day 33, heifers were randomly assigned to receive CONTROL (n = 95) or HiCON (n = 95) treatment, and estrous detection aids were applied. Heifers were exposed to AI 12 h after detection of estrus. Heifers not detected in estrus at location 1 received a second PGF2α injection 6 d after the initial PGF2α injection and were placed with fertile bulls. Heifers at location 2 that did not express estrus were administered 100 µg of GnRH i.m. and exposed to TAI 96 h after the initial PGF2α injection. Transrectal ultrasonography was used to diagnose PR/AI between 51 and 57 d after the initial PGF2α injection. The percentage of heifers exhibiting estrus during the estrus detection period was similar (P = 0.40) between CONTROL and HiCON treatments (82 vs. 87 ± 4%). Furthermore, PR/AI were similar (P = 0.62) between CONTROL and HiCON treatments (60 vs. 65 ± 5%). In summary, the 2 concentrations and corresponding routes of administration of PGF2α were similar in efficacy at synchronizing estrus in beef heifers.
两项实验旨在评估高浓度皮下注射前列腺素 F2α（PGF2α）与传统浓度肌肉注射前列腺素 F2α在安格斯基础肉牛同期发情方案中的效果。在实验 1 中，869 头安格斯基础肉牛在 8 个地点入组。所有的牛都接受了 7 天 CO-Synch+控释宫内节育器（CIDR）同期发情方案。在方案的第 7 天，牛接受了 100µg GnRH 肌肉注射，同时放置 CIDR 7 天。在第 0 天，CIDR 取出时，给牛贴上发情检测贴片，并在每个地点随机接受 2 种 PGF2α 处理之一：肌肉注射 5 毫升 Lutalyse（对照组；n=434）或皮下注射 2 毫升 Lutalyse HighCon（HiCON；n=435）。在 54±2 小时时再次注射 GnRH，牛进行定时人工授精（TAI）。通过确定发情检测贴片的激活，在 TAI 时评估牛的发情活动。通过直肠超声检查在 TAI 后 35 至 55 天诊断妊娠率至人工授精（PR/AI）。对照组和 HiCON 处理之间发情天数（0 天至 TAI）之间的差异不显著（P=0.68）（47% vs. 46±4%，分别）。此外，PR/AI 之间也相似（P=0.65）（46% vs. 45±3%，分别）。在实验 2 中，190 头安格斯基础肉牛在 2 个地点入组。牛接受了醋酸甲地孕酮（MGA）-PGF2α 方案，从第 1 天到第 14 天每天给牛提供 0.5 毫克 MGA。在第 33 天，牛随机接受对照组（n=95）或 HiCON 组（n=95）处理，并贴上发情检测贴片。牛在检测到发情后 12 小时接受人工授精。在第 1 个地点未发情的牛在初始 PGF2α 注射后 6 天接受第二次 PGF2α 注射，并与可繁殖公牛配种。第 2 个地点未发情的牛肌肉注射 100µg GnRH，在初始 PGF2α 注射后 96 小时接受 TAI。直肠超声检查用于诊断初始 PGF2α 注射后 51 至 57 天的 PR/AI。发情检测期内发情的牛比例在对照组和 HiCON 处理之间相似（P=0.40）（82% vs. 87±4%，分别）。此外，PR/AI 之间也相似（P=0.62）（60% vs. 65±5%，分别）。总之，在安格斯基础肉牛同期发情方案中，PGF2α 的 2 种浓度和相应的给药途径在功效上相似。
