EFFECTS OF AMINO-ACIDS ON DEVELOPMENT IN-VITRO OF CLEAVAGE-STAGE BOVINE EMBRYOS INTO BLASTOCYSTS

Effects of amino acids on early bovine embryo development in vitro wer e examined using a chemically-defined, protein-free culture medium. Bo vine embryos produced in vitro were cultured from 18 h to 72 h post in semination in a simple medium containing lactate as the only energy so urce except for the amino acid treatments. Subsequently, embryos were transferred to TCM-199 supplemented with serum for blastocyst developm ent to substantiate their developmental competence. Treatments were: ( 1) non-essential amino acids from TCM-199 (NEA); (2) essential amino a cids from TCM-199 (EA); (3) NEA+EA; (4) Eagle's minimum essential medi um amino acids (MEM AA); (5) 11 amino acids present in HECM-6 (11 AA); and (6) 0.2 mM glutamine (GLN). A higher proportion of embryos (perce ntage of inseminated oval cleaved to the greater than or equal to 8-ce ll stage by 72 h post insemination in NEA (56.7%), EA (41.2%), 11 AA ( 40.3%) and GLN (51.1%) than in either NEA+EA (30.0%) or MEM AA (33.1%) . However, after transfer to complex medium, embryos that had develope d in EA, as well as those in MEM AA or NEA+EA, produced significantly fewer blastocysts (37.1%, 34.4% and 25.6% respectively) than those in NEA (52.7%), GLN (48.9%) or 11 AA (37.7%). The ability of blastocysts to hatch from their zonae pellucidae was also affected by amino acid t reatment during cleavage stages. The present study indicates that the addition of NEA or GLN or 11 AA to a chemically-defined culture medium during the cleavage phase of bovine embryo development increases thei r subsequent ability to reach the blastocyst stage. These data have im plications for understanding the nutritional needs of bovine embryos p roduced in vitro and for optimizing the composition of culture media t o support their development.