IN-VITRO PRODUCTION OF VIABLE BOVINE BLASTOCYSTS IN MEDIA SUPPLEMENTED WITH RABBIT-ORIGINATED PRODUCTS

This study aimed at producing viable bovine blastocysts by IVM, IVF an d IVC, in media without addition of bovine-originated products. Bovine serum albumin (BSA) was replaced by polyvinyl alcohol in washing medi a, fetal calf serum (FCS) by rabbit serum during maturation and cultur e, BSA by rabbit serum albumin in fertilization and culture media. The effect of substituting rabbit protein sources for bovine ones was tes ted on nuclear maturation, fertilization and developmental rates, and on the quality of the blastocysts obtained. The proportion of oocytes reaching metaphase II (MII) after maturation in TCM 199 containing epi dermal growth factor was similar when supplemented with FCS (90/96) or with rabbit serum (92/99). The rate of 2 pronuclei formation was simi lar after sperm preparation and fertilization in Tyrode's medium suppl emented with BSA (70/97) or rabbit albumin (70/94). In a third set of experiments, a total of 792 oocytes was matured, fertilized and cultur ed in media supplemented with bovine (standard) or rabbit products. Em bryos were co-cultured with their own cumulus cells in synthetic ovidu ct fluid medium supplemented with serum at Day 3 post insemination. Th e proportion of cleaved and 5 to 8-cell stage embryos at Day 3 and the blastocyst yield on Day 8 were similar under standard and bovine addi tive-free conditions (cleavage: 81 vs 80 %, 5 to 8-cell stage: 49 vs 4 4%, blastocysts: 37 versus 30%). Blastocysts produced under bovine add itive-free conditions were viable since a calf was born after the tran sfer of a frozen embryo. Replacement of bovine products by rabbit orig inating ones resulted in a 0.5-d delay in blastocyst detection. Day 8 blastocysts produced in media containing rabbit products had a signifi cantly lower number of cells (101 +/- 7) than those produced under sta ndard conditions (120 +/- 6), possibly because of the difference in bl astocyst age. In conclusion, the protocol presented here allows for th e efficient production of viable bovine blastocysts under conditions t hat reduce the risk of disease transmission. (C) 1997 by Elsevier Scie nce Inc.