Department of Dairy Science, University of Wisconsin-Madison, Madison 53706, USA.
J Dairy Sci. 2013 May;96(5):2873-82. doi: 10.3168/jds.2012-5895. Epub 2013 Mar 1.
Reproductive management programs that synchronize ovulation can ovulate a smaller than normal follicle, potentially resulting in inadequate progesterone (P4) concentrations after artificial insemination (AI). Ovulation of the dominant follicle of the first follicular wave with human chorionic gonadotropin (hCG) treatment can produce an accessory corpus luteum and increase circulating P4 concentrations. This manuscript reports the results of 2 separate analyses that evaluated the effect of hCG treatment post-AI on fertility in lactating dairy cows. The first study used meta-analysis to combine the results from 10 different published studies that used hCG treatment on d 4 to 9 post-AI in lactating dairy cows. Overall, pregnancies per artificial insemination (P/AI) were increased 3.0% by hCG treatment post-AI [34% (752/2,213) vs. 37% (808/2,184); Control vs. hCG-treated, respectively]. The second study was a field research trial in which lactating Holstein cows (n=2,979) from 6 commercial dairy herds were stratified by parity and breeding number and then randomly assigned to one of 2 groups: control (no further treatment, n=1,519) or hCG [Chorulon i.m.: 2,000 IU (in 3 of the herds) or 3,300 IU (in 3 herds); n=1,460] on d 5 after a timed AI (ovulation synchronized with Ovsynch, Presynch-Ovsynch, or Double-Ovsynch). In a subset of cows, the hCG profile and P4 changes were determined. Treatment with hCG increased P4 (4.3 vs. 5.3 ng/mL on d 12). Pregnancies per AI were greater in cows treated with hCG (40.8%; 596/1,460) than control (37.3%; 566/1,519) cows. Interestingly, an interaction among treatment and parity was observed; primiparous cows had greater P/AI after hCG (49.7%; 266/535) than controls (39.5%; 215/544). In contrast, older cows receiving hCG (35.7%; 330/925) had similar P/AI to controls (36.0%; 351/975).Thus, targeted use of hCG on d 5 after TAI enhances fertility about 3.0% (based on meta-analysis) to 3.5% (based on our field trial). Surprisingly, this fertility-enhancing effect of hCG was very large in first-lactation cows but not observed in older cows in the field study. Future research is needed to confirm these intriguing results and to determine why older cows did not have improved fertility after hCG treatment.
生殖管理方案可同步排卵，使卵泡排卵小于正常大小，潜在地导致人工授精（AI）后孕激素（P4）浓度不足。用人绒毛膜促性腺激素（hCG）处理第一卵泡波的优势卵泡可产生副黄体并增加循环 P4 浓度。本手稿报告了 2 项独立分析的结果，这些分析评估了 AI 后 hCG 处理对泌乳奶牛生育力的影响。第一项研究使用荟萃分析结合了 10 项不同的已发表研究结果，这些研究在泌乳奶牛 AI 后第 4 至 9 天使用 hCG 处理。总体而言，AI 后 hCG 处理使每头人工授精的妊娠率（P/AI）增加了 3.0%[34%（752/2,213）与 37%（808/2,184）；分别为对照和 hCG 处理]。第二项研究是一项现场研究试验，其中 6 个商业奶牛场的泌乳荷斯坦奶牛（n=2,979）按胎次和配种次数分层，然后随机分为两组：对照组（无进一步治疗，n=1,519）或 hCG[Chorulon i.m.：2,000 IU（在 3 个牧场）或 3,300 IU（在 3 个牧场）；n=1,460]在定时 AI 后第 5 天（通过 Ovsynch、Presynch-Ovsynch 或 Double-Ovsynch 同步排卵）。在一部分奶牛中，确定了 hCG 曲线和 P4 变化。hCG 处理增加了 P4（第 12 天为 4.3 与 5.3ng/mL）。hCG 处理的奶牛的每头 AI 妊娠率（40.8%；596/1,460）高于对照组（37.3%；566/1,519）。有趣的是，观察到处理和胎次之间存在交互作用；初产奶牛的 hCG 处理后 P/AI 更高（49.7%；266/535）比对照组（39.5%；215/544）高。相比之下，接受 hCG 治疗的较老奶牛（35.7%；330/925）的 P/AI 与对照组（36.0%；351/975）相似。因此，在 TAI 后第 5 天靶向使用 hCG 将生育力提高约 3.0%（基于荟萃分析）至 3.5%（基于我们的现场试验）。令人惊讶的是，这种 hCG 的生育增强作用在初产奶牛中非常大，但在现场研究中未在较老的奶牛中观察到。需要进一步研究来证实这些有趣的结果，并确定为什么较老的奶牛在 hCG 处理后没有改善生育能力。
