Department of Dairy Science, University of Wisconsin-Madison, Madison 53706, USA.
Department of Animal Science, Cornell University, Ithaca, NY, USA.
Theriogenology. 2018 Jul 1;114:165-172. doi: 10.1016/j.theriogenology.2018.03.037. Epub 2018 Mar 31.
Our objective is to overview the research that lead to the development of fertility programs for high-producing lactating dairy cows using only GnRH and Prostaglandin F (PGF), such as Ovsynch with a focus on the role of progesterone in fertility. A key factor affecting fertility to timed-AI is the response to each hormonal treatment of the Ovsynch protocol. Although not required for fertility, cows ovulating to the first GnRH treatment of the Ovsynch protocol (G1) have greater P/AI than cows failing to ovulate. The association between progesterone concentrations at each treatment during the Ovsynch protocol and fertility is reviewed, and data from 7792 cows from 14 studies are presented. Overall, medium P4 (between 0.5 and 6 ng/mL) at G1, high P4 concentrations (>1.0 ng/mL) at the PGF, and low P4 concentrations (<0.4 ng/mL) at final GnRH (G2) are associated with greater P/AI. The use of presynchronization treatments that increase the percentage of cows initiating the Ovsynch protocol during early diestrous increases the percentage of cows with medium P4 concentrations at G1 and with high P4 concentration at PGF. Some cows, however, fail to completely undergo luteal regression after a single PGF treatment, particularly cows that initiate the Ovsynch protocol in a low P4 environment and cows with a young (d 6) CL at the time of treatment with PGF. Addition of a second PGF treatment increased the percentage of cows with complete luteal regression and P/AI. The use of fertility programs that include the concepts described in this review have resulted in more P/AI than inseminating cows after an induced estrus at first insemination. In addition, extending these concepts to strategies for resynchronization of ovulation and the implementation of an aggressive reproductive management program for first and subsequent inseminations results in reproductive performance that is unprecedented for high-producing Holstein dairy cows.
我们的目标是综述仅使用 GnRH 和前列腺素 F（PGF）开发高产泌乳奶牛繁殖方案的研究，如 Ovsynch，并重点关注孕激素在繁殖中的作用。影响定时人工授精（AI）受孕率的一个关键因素是奶牛对 Ovsynch 方案中每一种激素处理的反应。尽管不是受孕所必需的，但在 Ovsynch 方案中首次 GnRH 处理（G1）时排卵的奶牛的 P/AI 高于未排卵的奶牛。综述了 Ovsynch 方案中每个处理时孕激素浓度与繁殖力之间的关系，并提供了来自 14 项研究的 7792 头奶牛的数据。总体而言，G1 时中等 P4（0.5-6ng/mL 之间）、PGF 时高 P4 浓度（>1.0ng/mL）和 G2 时低 P4 浓度（<0.4ng/mL）与 P/AI 较高相关。使用增加奶牛在发情早期开始 Ovsynch 方案的同期发情处理的方法，可以增加 G1 时具有中等 P4 浓度和 PGF 时具有高 P4 浓度的奶牛比例。然而，一些奶牛在单次 PGF 处理后不能完全经历黄体退化，尤其是在低 P4 环境中开始 Ovsynch 方案的奶牛和在 PGF 处理时具有年轻（第 6 天）CL 的奶牛。添加第二次 PGF 处理增加了完全黄体退化和 P/AI 的奶牛比例。使用包括本综述中描述的概念的繁殖方案比在首次配种时进行诱导发情后配种的 P/AI 更高。此外，将这些概念扩展到排卵同步化策略以及首次和随后配种的积极繁殖管理方案的实施，可使高产荷斯坦奶牛的繁殖性能达到前所未有的水平。
