Saint-Dizier M, Legendre A-C, Driancourt M-A, Chastant-Maillard S
AgroParisTech, UFR Génétique Elevage Reproduction, Paris Cedex 05, France; INRA, UMR 85 Physiologie de la Reproduction et des Comportements, Nouzilly, France.
Reprod Domest Anim. 2014 Dec;49(6):920-5. doi: 10.1111/rda.12401. Epub 2014 Sep 15.
Luteolysis before the time of maternal recognition of pregnancy is one cause of low fertility in high-producing dairy cows. The objective of this study was to assess whether induction of a secondary corpus luteum (CL) late in the luteal phase would delay the time of luteolysis. Twenty high-producing Holstein cows were synchronized to ovulation (Day 0) with the Ovsynch protocol and received hCG (1500 IU im) on Day 12. Corpora lutea formation (as evaluated by ultrasonography) and plasma P4 concentrations were monitored from Days 4 to 36. hCG treatment induced the formation of one secondary CL (CL2) in 11 of 20 cows (55%) from the dominant follicle (mean diameter: 14.2 ± 0.9 mm) of two-wave (3/11) and three-wave (8/11) cycles. The maximal diameter of the CL2 (23.3 ± 1.9 mm) was reached approximately 6 days after hCG treatment and was correlated with its structural lifespan (p < 0.01). Cows that formed a CL2 after hCG had higher mean plasma P4 concentrations on Day 14 (+4.5 ng/ml) and Day 18 (+3.0 ng/ml) compared with cows without CL2 (p < 0.05). The structural regression of CL2 begun approximately 8 days after that of the CL1, and the median time at which the first drop in circulating P4 levels occurred was later in cows that formed a CL2 than in those that did not (Day 26 vs Day 18; p < 0.01). Thus, the induction of a CL2 by hCG on Day 12 might reduce the risk of premature luteolysis in high-producing dairy cows after insemination.
在母体识别妊娠之前发生黄体溶解是高产奶牛繁殖力低下的一个原因。本研究的目的是评估在黄体期后期诱导形成次级黄体（CL）是否会延迟黄体溶解的时间。20头高产荷斯坦奶牛通过Ovsynch方案同步排卵（第0天），并在第12天接受hCG（1500 IU，肌肉注射）。从第4天到第36天监测黄体形成（通过超声检查评估）和血浆P4浓度。hCG处理使20头奶牛中的11头（55%）从两波（3/11）和三波（8/11）周期的优势卵泡（平均直径：14.2±0.9 mm）中诱导形成了一个次级黄体（CL2）。CL2的最大直径（23.3±1.9 mm）在hCG处理后约6天达到，并且与其结构寿命相关（p<0.01）。与未形成CL2的奶牛相比，hCG处理后形成CL2的奶牛在第14天（+4.5 ng/ml）和第18天（+3.0 ng/ml）的平均血浆P4浓度更高（p<0.05）。CL2的结构退化大约在CL1之后8天开始，循环P4水平首次下降的中位时间在形成CL2的奶牛中比未形成CL2的奶牛更晚（第26天对第18天；p<0.01）。因此，在第12天用hCG诱导形成CL2可能会降低高产奶牛授精后过早黄体溶解的风险。
