Exposure of bovine zygotes to serum in a two-phase in vitro culture system adversely affects cleavage rate and cell number of embryos produced

Abstract

The number of cells in bovine and ovine embryos is reduced when steer serum which can generate high concentrations of ammonia in vitro is included in the culture system (Kuran et al., 1998). Moreover, production of embryos in synthetic oviduct fluid (SOF) medium supplemented with this serum causes fetal oversize (Sinclair et al., 1998). The present study investigated the effect of the same high ammonia-producing steer serum in a two-phase culture system on bovine embryo development and blastocyst cell numbers.The experimental design was a 2 x 2 factorial with 5 replicates and involved a total of 928 bovine oocytes that were matured and fertilized in vitro (IVF = Day 0). Presumptive zygotes were cultured in SOF supplemented with 10% v/v steer serum (SOF+SS; n=461) or with amino acids plus 0.4% w/v crystalline BSA (SOFaaBSA; n=467) for an initial period of 48 h following IVF.