Stevenson J S, Tiffany S M, Inskeep E K
Department of Animal Sciences and Industry, Kansas State University, Manhattan, Kansas 66506-0201, USA.
J Dairy Sci. 2008 Aug;91(8):3092-101. doi: 10.3168/jds.2008-1027.
The objectives were to determine whether a single injection of either human chorionic gonadotropin (hCG) or GnRH would: 1) increase ancillary formation of new luteal structures, 2) increase serum concentrations of progesterone, and 3) increase pregnancy survival in dairy females treated once between 26 and 71 d of pregnancy. A total of 421 cows were enrolled between January and November 2001, with 92, 106, and 223 females (included 68 nulliparous heifers at 1 location) treated at the 3 locations. Upon diagnosis of pregnancy, females were allocated randomly to receive 100 microg of GnRH, 1,000 IU of hCG, or 2 mL of saline. Blood samples were collected at 0, 1, 2, and 4 wk after treatment, and pregnancy status was reassessed at 1, 2, and 4 wk. New luteal structures were formed in 23.8% of cattle, with hCG (50%) and GnRH (26%) being more effective than saline (7%). Treatment had no effect on the proportion of females forming 2 new luteal structures (7.6%), and 36.2% of all induced structures regressed during the 4-wk study period. Pregnancy losses were unaffected by treatment, stage of pregnancy, or number of induced luteal structures but were nearly 9-fold greater in females in which induced luteal structures regressed. No loss occurred in females having 2 new luteal structures. Pregnancy losses decreased quadratically from 30 to 42 d. Serum progesterone did not differ among treatments, but among females forming new luteal structures, progesterone was greater at 1 (7.2 +/- 0.3 vs. 6.3 +/- 0.2 ng/ mL) and 2 wk (7.0 +/- 0.3 vs. 6.1 +/- 0.2 ng/mL) after treatment. Progesterone at the first pregnancy diagnosis was predictive of imminent pregnancy loss; the lower the initial progesterone, the sooner subsequent loss was observed. The right ovary was dominant in the location of new luteal structures. Regression of new luteal structures occurred more often on the left ovary and contra-lateral to the corpus luteum of pregnancy (53.2 vs. 22%). In conclusion, treatment of dairy cattle with either GnRH or hCG failed to prevent pregnancy loss, but concentrations of progesterone were predictive of subsequent pregnancy loss.
研究目的是确定单次注射人绒毛膜促性腺激素（hCG）或促性腺激素释放激素（GnRH）是否会：1）增加新黄体结构的辅助形成；2）提高血清孕酮浓度；3）提高在妊娠26至71天期间接受过一次治疗的奶牛的妊娠存活率。2001年1月至11月期间共纳入421头奶牛，在3个地点分别对92头、106头和223头母牛（其中1个地点包括68头未产小母牛）进行了治疗。确诊怀孕后，将母牛随机分配接受100微克GnRH、1000国际单位hCG或2毫升生理盐水。治疗后0、1、2和4周采集血样，并在1、2和4周重新评估妊娠状态。23.8%的母牛形成了新的黄体结构，hCG组（50%）和GnRH组（26%）比生理盐水组（7%）更有效。治疗对形成2个新黄体结构的母牛比例（7.6%）没有影响，在为期4周的研究期间，所有诱导形成的黄体结构中有36.2%发生了退化。妊娠损失不受治疗、妊娠阶段或诱导黄体结构数量的影响，但诱导黄体结构退化的母牛的妊娠损失几乎高出9倍。有2个新黄体结构的母牛没有发生妊娠损失。妊娠损失在30至42天呈二次方下降。各治疗组血清孕酮无差异，但在形成新黄体结构的母牛中，治疗后1周（7.2±0.3对6.3±0.2纳克/毫升）和2周（7.0±0.3对6.1±0.2纳克/毫升）时孕酮水平更高。首次妊娠诊断时的孕酮水平可预测即将发生的妊娠损失；初始孕酮水平越低，随后观察到损失的时间越早。新黄体结构主要位于右侧卵巢。新黄体结构的退化更多发生在左侧卵巢且与妊娠黄体对侧（53.2%对22%）。总之，用GnRH或hCG治疗奶牛未能预防妊娠损失，但孕酮浓度可预测随后的妊娠损失。
