Lee C N, Critser J K, Ax R L
J Dairy Sci. 1985 Jun;68(6):1463-70. doi: 10.3168/jds.S0022-0302(85)80984-X.
Gonadotropin-releasing hormone administered at breeding enhances fertility of dairy cows, so a study was designed to evaluate the mechanism for enhanced fertility following administration of gonadotropin-releasing hormone at first postpartum breeding. Twenty-four cows were assigned randomly to one of two treatments, 100 micrograms of gonadotropin-releasing hormone intramuscular or saline vehicle intramuscular at insemination. Blood samples for luteinizing hormone assay were taken at 2-h intervals prior to breeding and .5-h intervals for 3 h after insemination. Composite morning milk samples for progesterone assay were collected for 30 days after insemination or until next estrus. Cows given gonadotropin-releasing hormone had higher luteinizing hormone concentrations in blood serum following treatment than cows given saline, 13.2 versus 3.0 ng/ml. There was no relationship between luteinizing hormone and subsequent conception. Progesterone for cows that became pregnant was higher throughout sampling days. Mean progesterone concentrations were 4.6 versus 2.2 ng/ml in pregnant and nonpregnant cows during the first 4 days after insemination. Cows treated with gonadotropin-releasing hormone that conceived had higher progesterone than other cows, and that was evident at the first 4 days postbreeding.
在配种时注射促性腺激素释放激素可提高奶牛的繁殖力，因此设计了一项研究来评估产后首次配种时注射促性腺激素释放激素后繁殖力提高的机制。将24头奶牛随机分为两种处理组之一，在授精时分别肌肉注射100微克促性腺激素释放激素或生理盐水。在配种前每隔2小时采集一次血样用于促黄体生成素测定，在授精后3小时内每隔0.5小时采集一次血样。在授精后30天或直到下次发情时，采集混合的早晨牛奶样本用于孕酮测定。注射促性腺激素释放激素的奶牛在处理后血清中的促黄体生成素浓度高于注射生理盐水的奶牛，分别为13.2 ng/ml和3.0 ng/ml。促黄体生成素与随后的受孕之间没有关系。怀孕奶牛的孕酮在整个采样期间都较高。在授精后的前4天，怀孕奶牛和未怀孕奶牛的平均孕酮浓度分别为4.6 ng/ml和2.2 ng/ml。注射促性腺激素释放激素且受孕的奶牛的孕酮高于其他奶牛，这在配种后的前4天很明显。
