Department of Animal Sciences and Industry, Kansas State University, Manhattan, Kansas, USA.
Theriogenology. 2010 Mar 1;73(4):449-59. doi: 10.1016/j.theriogenology.2009.09.027. Epub 2009 Dec 3.
We first determined a dose of human chorionic gonadotropin (hCG) sufficient to induce ovulation in lactating Holstein cows. Ovaries of 85 previously inseminated cows were mapped using transrectal ultrasonography 7 d before pregnancy diagnosis and assigned randomly to treatments of saline, 100 microg gonadotropin-releasing hormone (GnRH), or 500, 1000, 2000, or 3000 IU hCG. Appearance of new corpus luteum (CL) in response to > or = 1000 IU hCG was similar to that for GnRH but greater (P<0.001) than that for saline. Ovarian structures and serum progesterone then were monitored in 334 previously inseminated Holstein cows 0 and 7 d after treatment with GnRH, hCG (1000 IU), or saline. The incidence of ovulation was greater (P=0.01) after GnRH than after saline in cows having pretreatment progesterone<1 ng/mL, whereas in cows having progesterone > or = 1 ng/mL, GnRH or hCG was more (P=0.01) effective than saline, and hCG also differed from GnRH. Holstein cows of unknown pregnancy status in three herds were treated with either GnRH, hCG, or as controls to initiate an ovulation-resynchronization procedure 7 d before pregnancy diagnosis. In 1109 treated pregnant cows, pregnancy loss during 4 wk after treatment tended (P=0.06) to be greater in those treated with hCG. Treated cows (n=1343) diagnosed not pregnant were then given prostaglandin F(2alpha) and inseminated and received GnRH 72h later. A treatment by herd interaction (P=0.06) resulted in more pregnancies after GnRH in two herds and after hCG in one herd compared with saline. We concluded that (1) > or = 1000 IU hCG resulted in more CL than did treatment with saline, and the incidence of new CL after either GnRH or hCG depended on pretreatment progesterone status; (2) hCG tended to increase pregnancy loss in pregnant cows; and (3) pregnancies per artificial insemination after initiating resynchronization with either hCG or GnRH produced ambiguous results.
我们首先确定了人绒毛膜促性腺激素（hCG）的剂量，足以诱导哺乳期荷斯坦奶牛排卵。在妊娠诊断前 7 天，通过直肠超声对 85 头先前授精的奶牛的卵巢进行定位，并随机分配到盐水、100μg 促性腺激素释放激素（GnRH）或 500、1000、2000 或 3000IU hCG 的处理中。对 >或=1000IU hCG 的新黄体（CL）的出现与 GnRH 相似，但更大（P<0.001）。然后，在 GnRH、hCG（1000IU）或盐水处理后 0 和 7 天，对 334 头先前授精的荷斯坦奶牛的卵巢结构和血清孕酮进行监测。在预处理孕酮<1ng/mL 的奶牛中，GnRH 后排卵的发生率（P=0.01）高于盐水，而在孕酮>或=1ng/mL 的奶牛中，GnRH 或 hCG 比盐水更有效（P=0.01），hCG 也与 GnRH 不同。在三个牛群中，对未知妊娠状况的荷斯坦奶牛进行 GnRH、hCG 或对照处理，在妊娠诊断前 7 天开始排卵同步程序。在 1109 头接受治疗的怀孕奶牛中，治疗后 4 周内的妊娠丢失倾向（P=0.06）在接受 hCG 治疗的奶牛中更高。然后，未怀孕的接受治疗的奶牛（n=1343）接受前列腺素 F（2alpha）并授精，并在 72 小时后接受 GnRH。处理与牛群之间的交互作用（P=0.06）导致两个牛群中的 GnRH 治疗和一个牛群中的 hCG 治疗后妊娠率更高，而盐水治疗的妊娠率更低。我们得出结论：（1）hCG 的剂量>或=1000IU 会导致更多的 CL 形成，而 GnRH 或 hCG 处理后的新 CL 发生率取决于预处理孕酮状态；（2）hCG 会增加怀孕奶牛的妊娠丢失；（3）通过 hCG 或 GnRH 启动同步后，每次人工授精的妊娠率结果并不明确。
