Effects of Lipoic Acid Supplementation on Finishing Steer Growth Performance, Carcass Merit, Beef Tenderness, and Beef Retail Display Properties

Angus cross steers (n = 84; BW =325 ± 3 kg) were used to evaluate the effects of lipoic acid (LA) supplementation on growth performance, carcass merit, beef tenderness, and beef retail display properties. Treatments were control (no LA), 8 mg of LA/kg of BW per d (LA8), and 16 mg of LA/kg of BW per d (LA16). Lipoic acid was incorporated into an extruded corn flour pellet and top-dressed onto a finishing diet for 125 d. Steers were subsequently delivered to a commercial abattoir for harvest. Carcass data and left-side longissimus sections (6th to 12th rib) were collected from each carcass at 24 h post-mortem. Steaks from each longissimus section were analyzed for Warner-Bratzler shear force (WBSF) and color. Final BW of control steers was greater (P<0.01) than that of LA16 steers; final BW of LA8 steers was intermediate between the two. There were no treatment differences in ADG, DMI, or gain to feed ratio (G:F). Treatment had no effect on carcass weight, marbling score, longissimus area, kidney-pelvic-heart fat, or USDA yield grade. Subcutaneous fat thickness and the percentage of USDA Yield Grade 4 carcasses tended (P≤0.09) to be greater for LA16 steers than for control steers; LA8 carcasses were intermediate between control and LA16 steers in both categories. Mean WBSF values for steaks aged 21 d were less (P<0.01) for LA16 steers than for control and LA8 steers. Lipoic acid supplementation had negligible effects on subjective color scores of steaks aged from 7 to 21 d. Lipoic acid supplementation appeared to increase external fatness of beef carcasses.