Effect of trypsin treatment of in vitro fertilized bovine embryos on their subsequent survival and development.

Abstract

The object of this study was to determine whether several washings with trypsin affected the survival and development of in vitro fertilized (IVF) bovine embryos. The embryos developed to blastocysts 7-8 days after insemination, were washed 12 times in washing medium (modified Dulbecco's phosphate-buffered saline (mPBS) containing 20% fetal bovine serum (FBS): 25 mM Hepes TCM199 with Earle's salts = 1:1), or in a series of three washes in the washing medium, two in mPBS containing 0.3% bovine serum albumin (BSA), two in 0.25% trypsin in Hank's solution (without Ca++ and Mg++) for a total time in the trypsin of 60 to 90 sec and five in the washing medium. After washing, the embryos were either cultured in vitro or cryopreserved. The fresh and frozen-thawed embryos were either cultured for 72 hr in vitro for evaluating development or transferred nonsurgically to recipient cows. Development of fresh and frozen-thawed embryos in vitro in control-washed and trypsin-washed embryos did not differ. Pregnancy rates did not differ (P > 0.05) among recipient cows receiving control-washed or trypsin-washed embryos, and transferring fresh or frozen-thawed embryos. These results indicate that the treatment of bovine IVF embryos with trypsin during washing did not have a positive effect on embryonic development.