Explaining meat quality of bulls and steers by differential proteome and phosphoproteome analysis of skeletal muscle

Abstract

The objective of this study was to evaluate the differential proteome and phosphoproteome between bulls and steers during conversion of muscle to meat, as well as after 14 days of aging. Twelve male Nellore (Bos taurus indicus) calves were used, and six calves were randomly selected for surgical castration. Calves were fed the same diet and were harvested after 230 days on feed. Longissimus muscle was sampled just after stunning (0d postmortem), at deboning (1d postmortem) and after aging (14d postmortem) for differential proteome analysis. Castration upregulated (P < 0.05) the abundance of glycolytic enzymes, while the oxidative phosphorylation protein ATP5B was downregulated (P < 0.05). In addition, abundance of troponin T fast isoform (TNNT3) was upregulated by castration (P < 0.05), while the slow isoform (TNNT1) tended to be decreased (P < 0.10). The creatine kinase M-type was markedly fragmented postmortem. Abundance of phosphorylated PGM1 increased during the first 24 h postmortem and was highly correlated with carcass pH. Further, abundance of the phosphorylated myofibrillar proteins ACTA1 and MYLPF were positively correlated with sarcomere shortening. Overall, our finds demonstrated that abundance and phosphorylation of glycolytic enzymes are associated with changes in beef tenderness and intramuscular fat.