Abstract
In vitro exposure of bovine immature oocytes to Streptococcus agalactiae, Escherichia coli, Actinomyces pyogenes and Staphylococcus aureus were conducted to determine if these bacteria were removed from bovine immature oocytes by the standard procedures for washing, or the bacteria were recovered from the embryos during in vitro culture. All the exposed bacteria were recovered from the immature oocytes after in vitro exposure and subsequent washing. E.coli were recovered from matured oocytes and S.aureus were recovered from matured oocytes and the embryos during in vitro culture. The rates of cleavage and development to blastocyst of embryos were not different between bacteria exposed groups and controls (51.4-62.6% vs 52.5-58.4%, 4.6-14.4% vs 7.5-15.6%, respectively). It was concluded that neither of the standard procedures currently used for cleaning immature oocytes should be relied upon for insuring freedom exposed bacteria, thus indicating that effective antibiotics should be added to in vitro culture system for removing or killing bacteria adhered to oocytes or embryos.
