Beltman M E, Lonergan P, Diskin M G, Roche J F, Crowe M A
Veterinary Sciences Centre, UCD School of Agriculture, Food Science and Veterinary Medicine, Ireland.
Theriogenology. 2009 Apr 15;71(7):1173-9. doi: 10.1016/j.theriogenology.2008.12.014. Epub 2009 Feb 8.
Progesterone is essential for establishment and maintenance of pregnancy in mammals. The objective of this study was to examine the effect of elevating progesterone during the different physiological stages of early embryo development on embryo survival. Estrus was synchronized in cross-bred beef heifers (n=197, approximately 2-years old) and they were inseminated 12-18h after estrus onset (=Day 0). Inseminated heifers were randomly assigned to 1 of 3 treatments: (1) Control, n=69; (2) progesterone supplementation using a Controlled Internal Drug Release Device (CIDR) from Day 3 to 6.5, n=64; or (3) progesterone supplementation using a CIDR from Day 4.5 to 8, n=64. Body condition (BCS) and locomotion scores (scale of 1-5) were recorded for all animals. Animals with a locomotion score >/=4 (very lame) were excluded. Embryo survival rate was determined at slaughter on Day 25. Conceptus length and weight were recorded and the corpus luteum (CL) of all pregnant animals was dissected and weighed. Supplementation with exogenous progesterone increased (P<0.05) peripheral progesterone concentrations, but did not affect embryo survival rate compared with controls. Mean CL weight, conceptus length and conceptus weight were not different between treatments. There was a positive relationship (P<0.04) between the increase in progesterone concentrations from Days 3 to 6.5 and embryo survival rate in treated heifers and a similar trend existed between the increase from Days 4.5 to 8 (P<0.06). There was also a positive relationship (P<0.05) between the progesterone concentration on Day 6.5 and the embryo survival rate in treated heifers. A direct correlation was seen between locomotion score and embryo survival rate, with higher (P<0.05) early embryo survival rates in heifers with a lower locomotion score. In conclusion, supplementation with progesterone at different stages of early embryo development increased peripheral progesterone concentration and resulted in a positive association between changes in progesterone concentration during the early luteal phase and embryo survival rate. Supplementation with progesterone had no effect on either CL weight or conceptus size in pregnant animals. Lameness had a significant negative effect on early embryo survival.
孕酮对于哺乳动物妊娠的建立和维持至关重要。本研究的目的是检测在早期胚胎发育的不同生理阶段提高孕酮水平对胚胎存活的影响。对杂交肉牛小母牛（n = 197，约2岁）进行发情同步处理，在发情开始后12 - 18小时（=第0天）进行授精。授精后的小母牛被随机分配到3种处理中的1种：（1）对照组，n = 69；（2）从第3天至6.5天使用控制内部药物释放装置（CIDR）补充孕酮，n = 64；或（3）从第4.5天至8天使用CIDR补充孕酮，n = 64。记录所有动物的体况（BCS）和运动评分（1 - 5分制）。将运动评分≥4（非常跛）的动物排除。在第25天屠宰时测定胚胎存活率。记录孕体长度和重量，并解剖和称重所有怀孕动物的黄体（CL）。与对照组相比，补充外源性孕酮可提高（P < 0.05）外周孕酮浓度，但不影响胚胎存活率。各处理之间的平均CL重量、孕体长度和孕体重量没有差异。在处理过的小母牛中，从第3天至6.5天孕酮浓度的升高与胚胎存活率之间存在正相关（P < 0.04），从第4.5天至8天的升高之间也存在类似趋势（P < 0.06）。在处理过的小母牛中，第6.5天的孕酮浓度与胚胎存活率之间也存在正相关（P < 0.05）。运动评分与胚胎存活率之间存在直接相关性，运动评分较低的小母牛早期胚胎存活率较高（P < 0.05）。总之，在早期胚胎发育的不同阶段补充孕酮可提高外周孕酮浓度，并导致黄体早期孕酮浓度变化与胚胎存活率之间呈正相关。补充孕酮对怀孕动物的CL重量或孕体大小均无影响。跛行对早期胚胎存活有显著负面影响。
