Pugliesi G, Oliveria M L, Scolari S C, Lopes E, Pinaffi F V, Miagawa B T, Paiva Y N, Maio J R G, Nogueira G P, Binelli M
Department of Animal Reproduction, School of Veterinary Medicine and Animal Science, University of São Paulo, Pirassununga, Brazil.
Reprod Domest Anim. 2014 Feb;49(1):85-91. doi: 10.1111/rda.12231. Epub 2013 Sep 4.
Strategic supplementation of P4 may be used to increase conception rates in cattle, but timing of supplementation in relation to ovulation, mass of supplementary P4 and formulation of the P4-containing supplement has not been determined for beef cattle. Effects of supplementation of long-acting progesterone (P4) on Days 2 or 3 post-ovulation on development, function and regression of corpus luteum (CL) were studied in beef cattle. Cows were synchronized with an oestradiol/P4-based protocol and treated with 150 or 300 mg of long-acting P4 on Day 2 or 3 post-ovulation (6-7 cows/group). Colour-doppler ultrasound scanning and blood sample collection were performed from Day 2-21.5. Plasma P4 concentrations were greater (p < 0.05) from Day 2.5-5.5 in the Day 2-treated groups and from Day 3.5-5.5 in the Day 3-treated cows than in the control group. CL area and blood flow during Day 2-8.5 did not differ (p > 0.05) among groups, suggesting no effect of P4 treatment on luteal development. The frequency of cows that began luteolysis before Day 15 was greater (p < 0.04) in cows treated with 300 mg than in the controls, but there were no differences between non-treated and 150 mg-treated cows. The interval from pre-treatment ovulation to functional and structural luteolysis was shorter (p < 0.01) in the combined P4-treated groups than in the control cows. In conclusion, was showed for the first time that long-acting P4 supplementation on Day 2 or 3 post-ovulation increases P4 concentrations for ≥3 day, has no effect on luteal development, but anticipates the beginning of luteolysis in beef cattle.
战略性补充孕酮（P4）可用于提高母牛的受孕率，但对于肉牛而言，补充P4的时间与排卵的关系、补充P4的量以及含P4补充剂的配方尚未确定。本研究探讨了排卵后第2天或第3天补充长效孕酮（P4）对肉牛黄体（CL）发育、功能和退化的影响。采用基于雌二醇/P4的方案对母牛进行同期发情处理，并在排卵后第2天或第3天用150或300mg长效P4进行处理（每组6 - 7头母牛）。在第2 - 21.5天进行彩色多普勒超声扫描和采血。与对照组相比，第2天处理组在第2.5 - 5.5天、第3天处理组在第3.5 - 5.5天的血浆P4浓度更高（p < 0.05）。各组在第2 - 8.5天的CL面积和血流量无差异（p > 0.05），表明P4处理对黄体发育无影响。与对照组相比，300mg处理组在第15天前开始黄体溶解的母牛频率更高（p < 0.04），但未处理组和150mg处理组之间无差异。联合P4处理组从预处理排卵到功能性和结构性黄体溶解的间隔比对照母牛短（p < 0.01）。总之，首次表明排卵后第2天或第3天补充长效P4可使P4浓度在≥3天内升高，对黄体发育无影响，但可提前肉牛黄体溶解的开始时间。
