Modifications in media composition and antioxidant support influences in vitro produced bovine blastocyst inner cell mass and trophectoderm numbers

Most of the in vitro bovine embryo production work completed over the past several decades has relied on using a medium formulation developed based on the chemical composition of sheep oviduct fluid (SOFBE1). This work explored how changes in the composition of this medium (modSOFBE1) and the inclusion of five antioxidant molecules (5AO) affect in vitro bovine embryo development. Studies used cumulus oocyte complexes collected from abattoir-derived ovaries that underwent in vitro maturation and fertilization, then presumptive zygotes were placed into the various media formulations. No medium type or 5AO supplementation effects were observed on the percentage of zygotes that cleaved or the percentage of cleaved embryos that formed blastocysts. Trophectoderm (TE) cell numbers were increased in blastocysts cultured in modSOFBE1, and inner cell mass (ICM) numbers were increased in blastocyst developed in modSOFBE1+5AO. Sex ratio of blastocysts was not influenced by medium type and 5AO supplementation. This work provides evidence that improvements in the base SOFBE1 formulation and the addition of multiple antioxidants may not improve overall blastocyst development rates, but they may be a useful means for promoting TE and ICM cell numbers in blastocysts. These modifications to the cellular composition of blastocysts and other subsequent activities on post-transfer development that have yet to be described may offer us with new opportunities to improve post-transfer pregnancy success of in vitro produced bovine embryos.