Attempts to improve the yield of bovine blastocysts by incorporating insulin, selenium and transferrin in the In Vitro system.

Abstract

To produce an embryo via in vitro maturation, in vitro fertilization and in vitro culture methods it is vital to obtain consistent results and at the same time a large number of bias to cysts from the immature oocytes collected, especially when only a small pool of these oocytes are available. The aim of the present investigation was to improve maturation rates, fertilization rates and blastocyst production rates by adding insulin (10 µg/ml), selenium (10 ng/ml) or transferrin (10 µg/ml) to the media. These were added individually or in different combinations and a complete randomised block design was set up to account for block and day effects. It was hypothesised that each treatment would improve maturation and fertilization rates and blastocyst production rates. It was found that of the treatments added to the maturation medium, Selenium at 10 ng/ml improved maturation percentages (80.4% vs 61.8%) and also increased fertilization percentages (68.0% vs 58.4%) and the number of bias to cysts produced (24.6% vs 11.5%). None of the treatments had a beneficial effect on fertilization rates or on blastocyst production rates when added to the fertilization medium. The treatments added to the culture medium showed that Transferrin at 10 µg/ml or Transferrin in combination with Insulin and Selenium increased the percentage of bias to cysts produced by in vitro culture methods (35.3% and 31.5% vs 18.7%). The addition of Transferrin also increased the percentage of bias to cysts that hatched (21.9% vs 14.2%) showing an improvement in the viability of the blastocysts produced. It is recommended that the maturation medium should include Selenium at 10 ng/ml. The fertilization process should have none of the investigated substances added to it and the culture medium should include Transferrin at 10 µg/ml. This combination should optimize the number of viable blastocysts that are produced in a bovine in vitro system.