A new presynchronization system (Double-Ovsynch) increases fertility at first postpartum timed AI in lactating dairy cows
A new presynchronization system (Double-Ovsynch) increases fertility at first postpartum timed AI in lactating dairy cows
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DOI：
10.1016/j.theriogenology.2008.03.014
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发表时间：
2008-07-15
期刊：
影响因子：
2.8
通讯作者：
Wiltbank, M. C.
中科院分区：
文献类型：
--
作者：
Souza, A. H.;Ayres, H.;Wiltbank, M. C.
本研究评估了一种新的预同步方法，与presynch - ovsync相比，在ovsync - timing AI协议之前使用ovsync （double - ovsync）。将泌乳荷斯坦奶牛（n = 337）分为两个处理组：(1)预同步（n = 180），间隔14 d注射两次PGF， 12 d后进行非同步人工智能治疗；(2)双ovsync (n = 157)， 7 d后给予GnRH、PGF， 3 d后给予GnRH， 7 d后给予ovsync -timed AI方案。所有奶牛接受相同的ovsynchronous AI方案：在68 +/- 3 DIM（平均+/- SEM）时GnRH (G1)， PGF后7 d， PGF后56 h GnRH (G2)， AI后16 ~ 20 h。定时人工智能后39 ~ 45 d诊断妊娠。与Presynch-Ovsynch相比，双ovsynch增加了每个AI的怀孕率（P/AI） （49.7% vs 41.7%, P = 0.03）。令人惊讶的是，双ovsync只增加了初产奶牛的P/AI (65.2% vs 45.2%; P = 0.02)，而不是多产奶牛（37.5% vs 39.3%）。在87头奶牛中，分别在G1和7 d后进行卵巢超声检查和孕酮（P4）测量。双ovsync降低了P4 （= 3 ng/mL）低的奶牛比例（78.1% vs 52.3%）。因此，与标准的预同步方案相比，双ovsynch奶牛的预同步提高了初产奶牛的生育能力，这可能是由于非循环奶牛的排卵诱导和循环奶牛的同步改善。未来的研究需要更多的奶牛，以进一步验证双ovsynch的高生育率假设，并阐明该方案明显改变生育率的生理机制。(C) 2008爱思唯尔公司版权所有。
This study evaluated a novel presynchronization method, using Ovsynch prior to the Ovsynch-timed AI protocol (Double-Ovsynch) compared to Presynch-Ovsynch. Lactating Holstein (n = 337) cows, were assigned to two treatment groups: (1) Presynch (n = 180), two injections of PGF 14 d apart, followed by the Ovsynch-timed AI protocol 12 d later; (2) Double-Ovsynch (n = 157), received GnRH, PGF 7 d later, and GnRH 3 d later, followed by the Ovsynch-timed AI protocol 7 d later. All cows received the same Ovsynch-timed AI protocol: GnRH (G1) at 68 +/- 3 DIM (mean +/- SEM), PGF 7 d later, GnRH (G2) 56 h after PGF, and AI 16 to 20 h later. Pregnancy was diagnosed 39-45 d after timed AI. Double-Ovsynch increased the pregnancies per AI (P/AI) compared to Presynch-Ovsynch (49.7% vs 41.7%, P = 0.03). Surprisingly, Double-Ovsynch increased P/AI only in primiparous (65.2% vs 45.2%; P = 0.02) and not multiparous (37.5% vs 39.3%) cows. In a subset of 87 cows, ovarian ultrasonography and progesterone (P4) measurements were performed at G1 and 7 d later. Double-Ovsynch decreased the percentage of cows with low P4 (= 3 ng/mL) at PGF (78.1% vs 52.3%). Thus, presynchronization of cows with Double-Ovsynch increased fertility in primiparous cows compared to a standard Presynch protocol, perhaps due to induction of ovulation in non-cycling cows and improved synchronization of cycling cows. Future studies are needed, with a larger number of cows, to further test the hypothesis of higher fertility with Double-Ovsynch, and to elucidate the physiological mechanisms that underlie apparent changes in fertility with this protocol. (C) 2008 Elsevier Inc. All rights reserved.