In vitro culture of bovine embryos in Ménézo's B2 medium with or without coculture and serum: the normalcy of pregnancies and calves resulting from transferred embryos.

The present study was designed to test the efficacy, as assessed by blastocyst production, of culturing slaughterhouse-derived bovine oocytes in Ménézo's B2 (B2) medium with or without serum and with or without buffalo rat cell (BRL) coculture. In addition, OPU-derived oocytes were cultured in B2-BRL coculture with or without serum for the first 72 h or TCM 199-BRL coculture with serum and the resulting embryos were transferred into recipients. Culture in B2 plus serum resulted in more blastocysts than B2 without serum, but both treatments produced far fewer blastocysts than did B2-BRL coculture. In addition, B2 with or without serum produced embryos of a lower stage of development, lower quality and fewer cells than did B2-BRL coculture. Serum restriction for the first 72 h of B2-BRL coculture did not result in a detectable difference in blastocyst production during 7 or 8 days of culture relative to coculture with no serum restriction. Embryos produced in B2-BRL coculture with serum restriction resulted in pregnancy rates, percentage of male fetuses, abortions, and congenital problems similar to those from B2 or TCM 199-BRL coculture with no serum restriction.