Performance, muscle metabolites, and beef quality of Nellore cull cows subjected to different finishing feeding durations

This study evaluated the performance, muscle metabolites, and beef quality of Nellore cull cows subjected to different finishing feeding durations. Twenty Nellore cows (initial body weight of 477.4 ± 49.6 kg) were randomly assigned to the three treatments: six as the control group (D0), seven finishing-fed for 28 d (D28), and seven finishing-fed for 56 d (D56). Parameters including dry matter intake, shrunk body weight, empty body weight (EBW), hot carcass weight (HCW), carcass shrinkage, muscle metabolites, and meat quality parameters in different aging times (0AT, 7AT, and 14AT) were assessed. Cull cows subjected to D28 and D56 treatments had greater EBW (P < 0.001) than D0. However, greater HCW (P = 0.004) and back fat thickness (P = 0.005) were detected in only D56 treatment compared to D0 and D28 treatments. As a result, the carcass pH was lower in the D56 treatment (P = 0.002) compared to D0 and D28 treatments. The Longissimus lumborum muscle of cull cows finished for 28 and 56 d showed a higher concentration of sugars (glucose-6-phosphate and fructose-6-phosphate), glycerol, and amino acids (leucine, alanine, isoleucine, valine, and aspartate). In conclusion, as the finishing period and aging time increased, there was a corresponding improvement in fat content and meat tenderness, respectively.