Removal of hypotaurine from porcine embryo culture medium does not impair development of in vitro‐fertilized or somatic cell nuclear transfer‐derived embryos at low oxygen tension

Hypotaurine (HT) is a routine component of porcine embryo culture medium, functioning as an antioxidant, but its requirement may be diminished as most embryo culture systems now use 5% O2 instead of atmospheric (20%) O2. Our objective was to determine the effects of removing HT from the culture medium on porcine preimplantation embryo development. Embryos cultured in 20% O2 without HT had decreased blastocyst development compared to culture with HT or in 5% O2 with or without HT. Notably, differences in blastocyst development or total cell number were not detected between embryos cultured in 5% O2 with or without HT. After culture in 5% O2 without HT and embryo transfer, healthy fetuses were retrieved from two pregnancies on Day 42, confirming in vivo developmental competence. Transcript abundance of proapoptotic markers was decreased in embryos cultured without HT regardless of oxygen tension; however, assays for apoptosis did not demonstrate differences between groups. Additionally, no differences were observed in the development or apoptosis of somatic cell nuclear transfer‐derived embryos cultured in 5% O2 with or without HT. With decreased utility in 5% O2, removing HT from porcine embryo culture medium would also have economic advantages because it is undoubtedly the most expensive component. Hypotaurine is an antioxidant added to porcine embryo culture medium, and it is the most expensive component of the formulation. However, removal of hypotaurine did not decrease development of in vitro‐fertilized or somatic cell nuclear transfer‐derived embryos to the blastocyst stage when culture was conducted in 5% O2, and pregnancies were established after transferring embryos cultured without hypotaurine. Transcript abundance of proapoptotic markers was decreased in embryos cultured without hypotaurine, but differences in apoptosis between embryos cultured with or without hypotaurine were not observed at the cellular level.