Possible actions of methionine on embryonic development and postnatal phenotype of calves produced after embryo...

Methionine is an important amino acid for the preimplantation embryo and may serve as a developmental programming agent. Here, it was tested whether L-methionine concentration in culture medium used to produce bovine embryos in vitro influences blastocyst development, cell lineage allocation, and lipid metabolism in vitro, as well as pregnancy outcomes and postnatal traits following embryo transfer. Two concentrations were examined: 50 μM, which is similar to concentrations seen in oviductal and uterine fluid and is a concentration commonly used in culture media, and 114 μM, which is the average concentration of methionine measured in uterine fluid of dairy cows fed rumen-protected methionine. There were no effects of methionine concentration on development in vitro, including the percent of embryos becoming blastocysts, blastocyst cell number or lipid content. Pregnancy rate after transfer of fresh blastocysts to recipient cows was similar for blastocysts of both treatments. However, the pregnancy rate after transfer of cryopreserved blastocysts was higher for blastocysts produced with 50 μM methionine. There were no significant effects of treatment on calf phenotype. In conclusion, results do not support the idea that increasing the concentration of methionine in embryo culture medium beyond typical amounts will enhance the outcome of embryo transfer procedures in cattle based on the use of embryos produced in vitro.