Growth, development, and gene expression by in vivo- and in vitro-produced day 7 and 16 bovine embryos

The effects of the embryo production system on growth and transcription rate of day 7 and 16 bovine embryos were investigated. In vivo- (controls) and in vitro-produced (IVP) embryos were transferred to female recipients on day 7 of development, and were allowed to develop in a synchronous uterine environment to day 16. Embryonic transcripts for insulin-like growth factors-1 and -2 (IGF-1 and -2), their receptors (IGF-1r and -2r), facilitative glucose transporters-1 and -3 (Glut-1 and -3), and interferon-tau (IFN-tau) were determined by real-time quantitative PCR (TaqMan); gender diagnosis was performed on day 16 concepti only. On day 7, IVP embryos presented lower mRNA levels than controls (P < 0.05), but these differences were generally reduced on day 16. No IGF-1 transcripts were detected on day 7, but a low IGF-1 mRNA level was observed in day 16 embryos. In the IVP group, IFN-tau mRNA levels were lower on day 7 (P < 0.05), but higher than controls on day 16 (P < 0.05). Control embryos showed a temporal decrease in the relative transcription from day 7 to 16 (P < 0.05), except IGF-1 mRNA. On day 16, IVP concepti were shorter and displayed smaller embryonic discs (P < 0.05). Female concepti were generally smaller than males, and IGF-2r mRNA and growth were negatively correlated. The in vitro production of bovine embryos negatively affected the amount of gene expression on day 7 and the rate of development on day 16. Physical traits and transcriptional activity on day 16 were associated with one another, which appeared to be significant for growth and development.