Colazo M G, Gordon M B, Rajamahendran R, Mapletoft R J, Ambrose D J
Dairy Research and Technology Centre, Alberta Agriculture and Rural Development, Edmonton, AB, Canada.
Theriogenology. 2009 Jul 15;72(2):262-70. doi: 10.1016/j.theriogenology.2009.02.017. Epub 2009 Apr 14.
We compared the effects of porcine luteinizing hormone (pLH) versus gonadotropin-releasing hormone (GnRH) on ovulatory response and pregnancy rate after timed artificial insemination (TAI) in 605 lactating dairy cows. Cows (mean+/-SEM: 2.4+/-0.08 lactations, 109.0+/-2.5 d in milk, and 2.8+/-0.02 body condition score) at three locations were assigned to receive, in a 2x2 factorial design, either 100 microg GnRH or 25mg pLH im on Day 0, 500 microg cloprostenol (PGF) on Day 7, and GnRH or pLH on Day 9, with TAI 14 to 18h later. Ultrasonographic examinations were performed in a subset of cows on Days 0, 7, 10, and 11 to determine ovulations, presence of corpus luteum, and follicle diameter and in all cows 32 d after TAI for pregnancy determination. In 35 cows, plasma progesterone concentrations were determined 0, 3, 4, 5, 6, 7, and 12 d after ovulation. The proportion of noncyclic cows and cows with ovarian cysts on Day 0 were 12% and 6%, respectively. Ovulatory response to first treatment was 62% versus 44% for pLH and GnRH and 78% versus 50% for noncyclic and cyclic cows (P<0.01). Location, ovulatory response to first pLH or GnRH, cyclic status, presence of an ovarian cyst, and preovulatory follicle size did not affect pregnancy rate. Plasma progesterone concentrations after TAI did not differ among treatments. Pregnancy rate to TAI was greater (P<0.01) in the GnRH/PGF/pLH group (42%) than in the other three groups (28%, 30%, and 26% for GnRH/PGF/GnRH, pLH/PGF/GnRH, and pLH/PGF/pLH, respectively). Although only 3% of cows given pLH in lieu of GnRH on Day 9 lost their embryo versus 7% in those subjected to a conventional TAI using two GnRH treatments, the difference was not statistically significant. In summary, pLH treatment on Day 0 increased ovulatory response but not pregnancy rate. Cows treated with GnRH/PGF/pLH had the highest pregnancy rate to TAI, but progesterone concentrations after TAI were not increased. In addition, preovulatory follicle diameter did not affect pregnancy rate.
我们比较了猪促黄体激素（pLH）与促性腺激素释放激素（GnRH）对605头泌乳奶牛定时人工授精（TAI）后排卵反应和妊娠率的影响。来自三个地点的奶牛（平均±标准误：2.4±0.08胎次，产奶109.0±2.5天，体况评分2.8±0.02），采用2×2析因设计，于第0天肌肉注射100微克GnRH或25毫克pLH，第7天注射500微克氯前列醇（PGF），第9天注射GnRH或pLH，14至18小时后进行TAI。在部分奶牛的第0、7、10和11天进行超声检查，以确定排卵情况、黄体的存在、卵泡直径，并在所有奶牛TAI后32天进行妊娠判定。在35头奶牛中，测定排卵后0、3、4、5、6、7和12天的血浆孕酮浓度。第0天非周期性奶牛和患有卵巢囊肿的奶牛比例分别为12%和6%。pLH和GnRH首次治疗后的排卵反应分别为62%和44%，非周期性和周期性奶牛分别为78%和50%（P<0.01）。地点、对首次pLH或GnRH的排卵反应、周期性状态、卵巢囊肿的存在以及排卵前卵泡大小均不影响妊娠率。TAI后各处理组的血浆孕酮浓度无差异。GnRH/PGF/pLH组的TAI妊娠率（42%）高于其他三组（GnRH/PGF/GnRH组、pLH/PGF/GnRH组和pLH/PGF/pLH组分别为28%、30%和26%，P<0.01）。尽管第9天用pLH替代GnRH的奶牛中只有3%胚胎丢失，而采用两次GnRH治疗的传统TAI奶牛中这一比例为7%，但差异无统计学意义。总之，第0天进行pLH治疗可增加排卵反应，但不提高妊娠率。接受GnRH/PGF/pLH治疗的奶牛TAI妊娠率最高，但TAI后的孕酮浓度未升高。此外，排卵前卵泡直径不影响妊娠率。
