Influence of realimentation of mature cows on maturity, color, collagen solubility, and sensory characteristics.

Cull beef cows (n = 80) that had consumed similar grassland diets were assigned to one of four feeding periods (0, 28, 56, and 84 d) and subdivided into two groups fed either a high-energy, high-protein diet or a high-energy, low-protein diet. Treatments were designed to examine the effect of time on feed, dietary protein, and electrical stimulation on carcass traits, composition, shear force, sensory profile, collagen characteristics, and myoglobin state. Within 1 h of slaughter, the right side of each carcass was electrically stimulated, and the left side served as the control. The only trait influenced by protein level was longissimus muscle area, for which a high-protein diet resulted in larger (P < .05) longissimus muscle areas. Increased time on a high-energy diet increased USDA yield grade and sensory ratings; however, metmyoglobin and reduced myoglobin values decreased between 0 and 28 d on feed. Electrical stimulation improved lean color, shear force values, and sensory attributes. Electrical stimulation decreased shear force by 2.8 kg for 0-d carcasses. With subsequent days on feed, shear force values continued to decrease, but this effect was minimal in electrically stimulated carcasses. However, protein level did not significantly influence palatability and quality attributes. The greatest (P < .05) improvement in marbling score was observed in electrically stimulated carcasses from cows fed for 84 d. Additionally, feeding a high-protein diet for 84 d resulted in a slightly lower maturity score. Even though values for palatability and quality traits were improved by antemortem and postmortem treatments, the magnitude of improvement may not be great enough for steaks from mature fed cows to be considered as acceptable as steaks from young fed beef.