Sterry R A, Silva E, Kolb D, Fricke P M
Department of Dairy Science, University of Wisconsin, Madison, WI 53706, United States.
Theriogenology. 2009 Feb;71(3):534-42. doi: 10.1016/j.theriogenology.2008.08.020. Epub 2008 Oct 15.
The primary objective was to evaluate fertility of anovular dairy cows given GnRH 4 d after first postpartum timed AI (TAI). Secondary objectives were to determine ovulatory response to treatment, effect of treatment on serum progesterone (P(4)) concentrations, and the proportion with a short luteal phase. Lactating Holstein cows (n=1047) were submitted for first postpartum TAI using a Presynch+Ovsynch protocol. Anovular cows were identified from an initial 1047 lactating Holstein cows using transrectal ultrasonography, based on the absence of a CL at the first GnRH injection of a Presynch+Ovsynch protocol, and anovular cows were randomly assigned to receive either no further treatment (Control, n=85), or 100 microg of GnRH 4 d after TAI (GnRH treated; n=71). For GnRH treated cows, 51% responded by ovulating a follicle in response to GnRH treatment 4 d after TAI; however, pregnancies per AI (P/AI) did not differ between GnRH treated cows that ovulated (36%) compared to GnRH treated cows that did not ovulate (21%). There was a quadratic effect of P(4) at the PGF(2 alpha) injection of Ovsynch on P/AI, and cows with P(4)>or=1 ng/mL at the PGF(2 alpha) injection of Ovsynch had greater P/AI (41%) than cows with P(4)<1 ng/mL (12%); however, no treatment difference was detected. Overall, P/AI did not differ between control (30.1%) and GnRH treated (29.6%) treatments for synchronized cows. Although treatment of anovular cows with GnRH 4 d after TAI failed to improve fertility, variation among cows in serum P(4) at the PGF(2 alpha) injection of Ovsynch dramatically affected fertility of anovular dairy cows.
主要目标是评估首次产后定时人工授精（TAI）4天后给予促性腺激素释放激素（GnRH）的无排卵奶牛的繁殖力。次要目标是确定对治疗的排卵反应、治疗对血清孕酮（P4）浓度的影响以及黄体期短的比例。泌乳荷斯坦奶牛（n = 1047头）采用预同步+同期发情方案进行首次产后TAI。基于在预同步+同期发情方案的首次GnRH注射时无黄体，通过经直肠超声从最初的1047头泌乳荷斯坦奶牛中识别出无排卵奶牛，无排卵奶牛被随机分配接受不进一步治疗（对照组，n = 85头）或在TAI后4天接受100微克GnRH（GnRH治疗组；n = 71头）。对于GnRH治疗组的奶牛，51%在TAI后4天对GnRH治疗有卵泡排卵反应；然而，排卵的GnRH治疗组奶牛的每人工授精妊娠率（P/AI）（36%）与未排卵的GnRH治疗组奶牛（21%）之间没有差异。在同期发情的PGF2α注射时P4对P/AI有二次效应，在同期发情的PGF2α注射时P4≥1纳克/毫升的奶牛的P/AI（41%）高于P4＜1纳克/毫升的奶牛（12%）；然而，未检测到治疗差异。总体而言，同步奶牛的对照组（30.1%）和GnRH治疗组（29.6%）之间的P/AI没有差异。尽管在TAI后4天用GnRH治疗无排卵奶牛未能提高繁殖力，但在同期发情的PGF2α注射时奶牛血清P4的差异显著影响了无排卵奶牛的繁殖力。
