This study sought to establish whether treatment with the GnRH analog dephereline in the early luteal phase could be useful to improve fertility in repeat-breeder cows (>3 inseminations). Dephereline was given 5-7 days after insemination, and effects of both a single and elevated (2.5 times) dephereline dose on pregnancy and subsequent embryo survival determined in repeat-breeder lactating dairy cows. The study population comprised 810 cows: 399 repeat-breeder cows and 411 non repeat breeders. To determine the effects of treatment on the pregnancy rate, three study groups were established: Control, no treatment (n = 269), DEPH, single dephereline dose (100 μg) (n = 270), or 2.5DEPH, 2.5 dephereline doses (250 μg) (n = 271). Recorded pregnancy rates in these groups were 28.6% (77/269), 31.9% (86/270) and 39.1% (106/271), respectively. Binary logistic regression analysis revealed a significant effect of the interaction treatment x repeat breeder on the pregnancy rate. This meant that the single dose and control treatments led to a pregnancy likelihood of repeat-breeder cows reduced by factors of 0.47 and 0.34, respectively, when compared to the 2.5 dose treatment as reference. Treatment had no effects on non repeat breeders. Based on odds ratios, treatment given either as a single or 2.5 dose increased the probability of an additional corpus luteum (more corpora lutea than embryos) in pregnant cows by factors of 5 or 5.4, respectively. Treatment had no effect on embryo survival. Our findings support the hypothesis that dephereline treatment in the early luteal phase after AI improves fertility in repeat-breeder cows. A dephereline dose 2.5 times higher than normal led to improved pregnancy rates, thus overcoming the impacts of repeat-breeder syndrome. Importantly, both the single and 2.5 dephereline doses increased the chances of pregnant cows having an additional corpus luteum, likely favoring embryo survival.

中文翻译：

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在早期黄体期用高剂量的 GnRH 类似物 dephereline 治疗可提高重复育种奶牛的妊娠率

本研究旨在确定在早期黄体期用 GnRH 类似物 dephereline 治疗是否有助于提高重复育种奶牛的生育能力（> 3 次授精）。在受精后 5-7 天给予 Dephereline，并在重复育种泌乳奶牛中确定单一剂量和升高（2.5 倍）dephereline 剂量对妊娠和随后胚胎存活的影响。研究种群包括 810 头奶牛：399 头重复繁殖母牛和 411 头非重复繁殖母牛。为了确定治疗对妊娠率的影响，建立了三个研究组：对照组、未治疗组 (n = 269)、DEPH、单次去肾上腺素剂量 (100 μg) (n = 270) 或 2.5DEPH、2.5 次去肾上腺素剂量 ( 250 微克）（n = 271）。这些组的记录妊娠率分别为 28.6% (77/269)、31.9% (86/270) 和 39.1% (106/271)。二元逻辑回归分析揭示了交互处理 x 重复育种对妊娠率的显着影响。这意味着与作为参考的 2.5 剂量治疗相比，单剂量和对照治疗导致重复育种奶牛的怀孕可能性分别降低了 0.47 和 0.34 倍。处理对非重复育种者没有影响。根据比值比，单剂量或 2.5 剂量的治疗分别使怀孕奶牛产生额外黄体（比胚胎更多的黄体）的概率分别增加了 5 倍或 5.4 倍。治疗对胚胎存活没有影响。我们的研究结果支持这样的假设，即在人工授精后早期黄体期的 dephereline 治疗可提高重复育种奶牛的生育能力。Dephereline 剂量 2。比正常高 5 倍导致怀孕率提高，从而克服了重复繁殖者综合症的影响。重要的是，单次和 2.5 次 dephereline 剂量都增加了怀孕奶牛具有额外黄体的机会，可能有利于胚胎存活。