ATTEMPTS TO IMPROVE THE YIELD OF BOVINE BLASTOCYSTS BY INCORPORATING INSULIN, SELENIUM AND TRANSFERRIN IN THE IN-VITRO SYSTEM

The aim of the present investigation was to improve maturation, fertil isation and blastocyst production rates by adding insulin (10 mu g/ml) , selenium (10 ng/ml) or transferrin (10 mu g/ml) individually and in different combinations to in vitro culture media. The experiment was d ivided into three parts with the additives being included to: (A) the maturation medium where effects on maturation rates and the subsequent development of bovine oocytes were measured, (B) the fertilisation me dium, assessing fertilisation rates and further development and (C) th e culture medium where bovine embryo development was evaluated Seleniu m, when added to maturation medium, significantly (p < 0.01) improved maturation rates (80.4% vs 61.8%), fertilisation rates (68.0% vs 58.4% ) and the percentage of blastocysts produced (24.6% vs 11.5%). None of the treatments had a beneficial effect on fertilisation rate or blast ocyst production rate when added to the fertilisation medium. Incorpor ation of transferrin or transferrin in combination with insulin and se lenium in the culture medium, significantly (p < 0.05) increased the p ercentage of blastocysts produced (35.3% and 31.5% vs 18.7%). Transfer rin also significantly (p < 0.05) increased the percentage of blastocy sts that hatched (21.9% vs 14.2%), indicating an improvement in the vi ability of the blastocysts produced. By adding selenium to the maturat ion medium and transferrin to the culture medium the in vitro producti on of bovine blastocysts is improved.