Effects of oocyte quality and semen donor on the efficiency of in vitro embryo production in cattle

Abstract

The aim of the study was to determine whether immature bovine oocytes selected by morphology and BCB test (brilliant cresyl blue) and used for in vitro embryo production would increase the blastocyst rate when inseminated with sperm derived from bulls of reduced in vitro fertilizability. To relate oocyte quality and bull effect to blastocyst quality, morphology, ability for hatching and caspase-3 activity (marker of apoptosis) were evaluated.Both, oocytes originating from BCB+ and from Control COCs exhibited higher cleavage and blastocyst rates (P<0.001) compared with BCB- oocytes. Significant differences in cleavage and blastocyst rates between the two bulls were observed. The highest blastocyst rate was noticed for BCB+ oocytes, regardless the bull. Comparison of the caspase-3 activity shows a significant overbalance of blastocysts with high caspase-3 activity, regardless the stage of blastocyst development and their origin. Thus, using excellent quality oocytes and sperm with reduced in vitro fertilizability it was possible to some extent to overcome bull effect on embryo production.