Plasma Free Amino Acid Profiles During Fattening Period Predict Carcass Traits in Female Japanese Black Cattle: A...

Early prediction of carcass traits, particularly carcass weight and beef marbling score, is critical for optimizing beef production efficiency. We explored prediction models for these carcass traits using plasma free amino acid and related metabolite profiles during the midfattening period (20 months) in female Japanese Black cattle (n = 52). Stepwise multiple regression analysis and leave-one-out cross-validation were used to construct and evaluate the model. However, analyses that included all cattle were unsatisfactory, likely due to data variability and/or insufficient sample size. When cattle were categorized into two fattening durations, conventional (n = 28) and longer term (n = 24), prediction models for both carcass traits were successfully developed and validated, suggesting that differences in the fattening duration influenced the quality of the prediction models. From a total of 24 amino acids and six related metabolites, five to nine amino acids were selected as key predictors, emphasizing the dominant role of amino acids in this study. These findings suggested that plasma free amino acid profiles are potential practical predictors of carcass traits in beef production. Future studies with larger, regionally diverse datasets and varying fattening durations are essential to enable broader industrial applications.