Ealy A D, Drost M, Hansen P J
Dairy Science Department, University of Florida, Gainesville 32611.
J Dairy Sci. 1993 Oct;76(10):2899-905. doi: 10.3168/jds.S0022-0302(93)77629-8.
The objective of this study was to determine whether bovine embryos become more resistant to deleterious effects of maternal heat stress as early embryonic development progresses. Superovulated, lactating Holstein cows were bred by AI and assigned to be heat stressed on d 1, 3, 5, or 7 of pregnancy (d 0 = day of estrus) or not heat stressed (control). Embryos were retrieved from the uterus on d 8 and evaluated for viability and stage of development. Compared with embryos of control cows, embryos of cows receiving heat stress on d 1 had decreased viability and development. Maternal heat stress on other days had no detrimental effect on embryonic viability or stage of development. Bovine embryos become more resistant to adverse effects of maternal heat stress as pregnancy progresses; substantial resistance develops by d 3. This information may be useful in design of environmental modification systems that provide cooling at critical periods of gestation to enhance pregnancy rates during summer in hot climates.
本研究的目的是确定随着早期胚胎发育的进行，牛胚胎是否会对母体热应激的有害影响产生更强的抵抗力。对超排的泌乳荷斯坦奶牛进行人工授精，并将其分为在妊娠第1、3、5或7天接受热应激处理（第0天为发情日）或不接受热应激处理（对照组）。在第8天从子宫中取出胚胎，评估其活力和发育阶段。与对照组奶牛的胚胎相比，在第1天接受热应激处理的奶牛胚胎活力和发育情况有所下降。在其他日子进行母体热应激处理对胚胎活力或发育阶段没有不利影响。随着妊娠的进展，牛胚胎对母体热应激的不利影响产生更强的抵抗力；到第3天会形成显著的抵抗力。这些信息可能有助于设计环境调节系统，在妊娠关键期提供降温措施，以提高炎热气候下夏季的妊娠率。
