Association between donor animal category and amino acid profiles in bovine oocytes and embryos produced in vitro.

In vitro embryo production (IVP) is widely used in cattle breeding, however, pregnancy outcomes remain suboptimal, primarily due to variability in oocyte and embryo quality. This study evaluated the association of donor animal category with amino acid turnover in bovine oocytes and embryos and assessed its relationship with developmental competence. Cumulus-oocyte complexes (COCs) were collected via ovum pick-up from prepubertal heifers (8.4 ± 0.5 mo of age; n = 9), pubertal heifers (16.5 ± 0.5 mo of age; n = 10), and cows (25.5 ± 0.5 mo of age; n = 10). A total of 198, 324, and 286 COCs, respectively, were subjected to in vitro maturation, fertilization, and culture. Amino acid profiles in media were quantified using gas chromatography in at least 6 independent biological replicates per experimental group, where each replicate represented a separate culture well containing pooled oocytes or embryos. Oocytes from prepubertal heifers exhibited elevated alanine and glycine levels, whereas embryos derived from these donors showed increased levels of alanine, glutamic acid, and serine, together with greater depletion of essential amino acids such as valine, isoleucine, methionine, and cystine. In contrast, oocytes and embryos from pubertal heifers and adult cows exhibited more similar amino acid profiles. These metabolic differences were associated with oocyte quality, and embryo developmental outcomes, with the highest proportion of good quality oocytes and Day 7 blastocyst formation observed in adult cows. Specific amino acids - alanine, glycine, and asparagine - showed positive associations with oocyte quality in pubertal and adult donors. These results provide insight into the developmental limitations of prepubertal oocytes and may support future efforts to refine IVM and IVC protocols. In addition, the observed amino acid profiles suggest the potential of metabolomic biomarkers for improving embryo selection and IVP efficiency in cattle, although further validation is required.