Growth rate and finishing system alter beef color and early postmortem metabolism in Bos indicus crossbred cattle

The aim of this study was to explore the effects of growth rate and finishing system (feedlot or pasture) on postmortem muscle metabolism and subsequent beef color development. Seventy-two Angus × Nellore crossbred steers were randomly assigned to one of four treatment combinations: 1) feedlot, high growth rate (FH); 2) feedlot, low growth rate (FL); 3) pasture, high growth rate (PH) and 4) pasture, low growth rate (PL). Animals were harvested either at a constant body weight (BW; 530 kg) or days on feed (DOF; 140 d). PL cattle had darker (P < 0.001) lean, slower (P = 0.006) pH declines and greater (P = 0.005) ultimate (24 h) pH values, as well as lower glycolytic potentials (P = 0.019) in the Longissimus muscle compared to FH cattle when harvested based on DOF. Muscle from PH had similar muscle energy metabolism when subjected to an in vitro glycolysis system, and beef color attributes compared to those of FL cattle. Growth rate influenced postmortem beef metabolism and color attributes more notably when harvested at a constant BW endpoint compared to those harvested on a constant DOF. Both feeding regime and growth rate affected meat quality characteristics. These results demonstrate that feeding strategies should be carefully considered when attempting to optimize beef quality development, especially fresh color.