Culture of in vitro-produced bovine embryos with vitamin E improves development in vitro and after transfer to recipients

Detrimental effects of oxygen-derived free radicals on embryos during culture have been demonstrated in several species. Vitamin E occurs naturally in cell membranes and protects cells from oxidative stress. Under some conditions, vitamin C acts synergistically to enhance the antioxidant effects of vitamin E, a benefit that may be further enhanced by EDTA. The present experiments concerned culture of bovine embryos derived from in vitro-matured, fertilized oocytes with vitamin E, vitamin C, and EDTA in a chemically defined culture medium + 0.2% BSA at 5% O(2), 5% CO(2), and 90% N(2). In the first experiment, more zygotes developed to expanded blastocysts (17%, n = 224, P < 0.05) when culture medium contained 100 microM vitamin E than in control medium (11%, n = 234). Development to early, expanded, and hatched blastocysts was lower with vitamins E and C combined than with vitamin E alone (15%, 9%, and 2% vs. 24%, 17%, and 5%, respectively; P < 0.05), as was the mean number of cells per blastocyst (56 vs. 84, P < 0.05). Addition of EDTA (3 microM) failed to improve development over that in culture with vitamin E + vitamin C. In experiment 2, in vitro-produced embryos cultured 5.5 days in medium with or without 100 microM vitamin E were transferred nonsurgically to recipient cows and heifers and then collected nonsurgically 7 days later. Embryos cultured with vitamin E (n = 37) were approximately 63% larger in surface area than controls (1.16 mm(2) vs. 0.71 mm(2) surface area; n = 27, P < 0.04).