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

Abstract

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), 8mg of LA/kg of BW per d (LA8), and 16mg 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 24h 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.