Effect of casein phosphopeptides on fertilization in vitro of bovine oocytes matured in culture
1996
Nagai, T. (Tohoku National Agricultural Experiment Station, Morioka (Japan)) | Hori, N. | Abe, S. | Hirayama, M.
The present study examined the effects of casein phosphopeptides (CPPs), a mixture of alpha-CPP and beta-CPP, during fertilization processes in vitro on the ability of bull spermatozoa to penetrate in vitro matured bovine oocytes and on the subsequent development of the fertilized oocytes. Frozen-thawed spermatozoa with low (Bull A and B) and high (Bull C) fertilization rates confirmed by the conventional in vitro fertilization method were used for the experiments. In vitro matured oocytes were inseminated with the spermatozoa in fertilization medium containing 5 mM caffeine and heparin (10 units/ml) with or without addition of CPPs (1mg/ml). Addition of CPPs to the medium significantly enhanced the fertilization rates achieved with spermatozoa for Bulls A (79% with and 38% without CPPs) and B (45% with and 13% without CPPs), but had no distinct impact on the high fertilization rates (94-95%) observed for Bull C. After 7 days of culture,significantly higher rates of development to the blastocyst stage occurred with oocytes inseminated with spermatozoa A (20%) and B (6%) in the medium supplemented with CPPs than when inseminated in CPPs-free medium (4 and 0%, respectively). These results indicate that CPPs enhance both the ability of spermatozoa with low fertilizing ability to penetrate oocytes in vitro and the subsequent development of embryos to the blastocyst stage
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