Addition of granulocyte-macrophage colony-stimulating factor during in vitro oocyte maturation improves cattle in vitro embryo production

Abstract

In vitro embryo production (IVP) is a reproductive technology used in the cattle industry to increase the rate of genetic gain. The present study determined if addition of recombinant bovine granulocyte-macrophage colony-stimulating factor (rbGM-CSF) during in vitro oocyte maturation (IVM) could improve in vitro embryo production in cattle. Cumulus oocyte complexes (COCs) were aspirated from abattoir derived ovaries and matured in the absence or presence (10 ng/ml) of rbGM-CSF. Following IVM, COCs were fertilized and cultured in vitro, and embryo development assessed. The effects of rbGM-CSF on mitochondrial activity, glucose uptake, reactive oxygen species levels, and metabolic gene expression in COCs were examined. Compared with the control, addition of rbGM-CSF during IVM increased blastocyst development rate (+12 %; p < 0.01 and hatching blastocyst rate (+24 %; p < 0.05). Inclusion of rbGM-CSF also increased the number of cells within the inner cell mass (+27 %; p < 0.05), and the ratio of inner cell mass to trophectoderm cells (+14 %; p < 0.05) in resultant blastocyst-stage embryos. The total blastocyst cell number also tended to be higher in the rbGM-CSF group (+7 %; p < 0.1). Addition of rbGM-CSF increased mitochondrial activity in oocytes (+10 %; p < 0.05), and glucose uptake in both cumulus cells (+316 %; p < 0.05) and oocytes (+190 %; p < 0.05). There was no effect of rbGM-CSF on COC gene expression of metabolic related genes. In conclusion, we have shown that the addition of rbGM-CSF during IVM improves bovine IVP.