Beltman M E, Roche J F, Lonergan P, Forde N, Crowe M A
Veterinary Sciences Centre, UCD School of Agriculture, Food Science and Veterinary Medicine, Belfield, Dublin 4, Ireland.
Theriogenology. 2009 Oct 15;72(7):986-92. doi: 10.1016/j.theriogenology.2009.06.018. Epub 2009 Aug 28.
Two experiments were designed to evaluate models for generation of low circulating progesterone concentrations during early pregnancy in cattle. In Experiment 1, 17 crossbred heifers (Bos taurus) were assigned to either prostaglandin F(2alpha) (PGF(2alpha)) administration on Days 3, 3.5, and 4 (PG3; n=9) or to control (n=8). Blood samples were collected from heifers from Days 1 to 9 for progesterone assay. Progesterone concentrations were decreased (P<0.03) between 18 and 48h after first PGF(2alpha) treatment in heifers assigned to PG3 compared with that of controls. In Experiment 2, 39 crossbred heifers detected in estrus were inseminated (Day 0) and assigned to either (1) PGF(2alpha) administration on Days 3, 3.5, and 4 (PG3; n=10), (2) PGF(2alpha) administration on Days 3, 3.5, 4, and 4.5 (PG4; n=10), (3) Progesterone Releasing Intravaginal Device (PRID) insertion on Day 4.5 with PGF(2alpha) administration on Days 5 and 6 (PRID+PGF(2alpha); n=10), or (4) control (n=9). Blood samples were collected daily until Day 15, and conceptus survival rate was determined at slaughter on Day 16. Progesterone concentrations during the sampling period in the PG3 and PG4 groups did not differ but were less than that of controls (P<0.01). After an initial peak, progesterone concentrations in the PRID+PGF(2alpha) group were similar to that of controls. More heifers in the PG4 group (6 of 10) had complete luteal regression than did those in the PG3 group (3 of 10). Conceptus survival rate on Day 16 did not differ between groups. There was a significant correlation between progesterone concentration on Days 5 and 6 and conceptus size on Day 16. In summary, treatment with PGF(2alpha) on Days 3, 3.5, and 4 postestrus appeared to provide the best model to induce reduced circulating progesterone concentrations during the early luteal phase in cattle.
设计了两个实验来评估牛妊娠早期循环孕酮浓度低的生成模型。在实验1中，17头杂交小母牛（Bos taurus）被分配到在第3、3.5和4天给予前列腺素F（2α）（PGF（2α））（PG3组；n = 9）或作为对照组（n = 8）。从第1天到第9天采集小母牛的血样进行孕酮测定。与对照组相比，PG3组小母牛在首次PGF（2α）治疗后18至48小时之间孕酮浓度降低（P<0.03）。在实验2中，39头检测到发情的杂交小母牛进行授精（第0天），并被分配到以下组：（1）在第3、3.5和4天给予PGF（2α）（PG3组；n = 10），（2）在第3、3.5、4和4.5天给予PGF（2α）（PG4组；n = 10），（3）在第4.5天插入孕酮释放阴道装置（PRID）并在第5和6天给予PGF（2α）（PRID + PGF（2α）组；n = 10），或（4）对照组（n = 9）。每天采集血样直至第15天，并在第16天屠宰时确定胚胎存活率。PG3组和PG4组在采样期间的孕酮浓度没有差异，但低于对照组（P<0.01）。在最初的峰值之后，PRID + PGF（2α）组的孕酮浓度与对照组相似。PG4组（10头中的6头）比PG3组（10头中的3头）有更多的黄体完全退化。第16天各实验组的胚胎存活率没有差异。第5和6天的孕酮浓度与第16天的胚胎大小之间存在显著相关性。总之，发情后第3、3.5和4天用PGF（2α）处理似乎能提供诱导牛黄体早期循环孕酮浓度降低的最佳模型。
