Dietary supplementation of lipoic acid and its effect on immune response, growth performance, carcass merit, tenderness and retail display properties of beef steers

Packer et al. (1995) deemed lipoic acid (LA) as the universal antioxidant. They based this title on LA's ability to scavenge a wide range of free radicals; to directly and indirectly regenerate antioxidants such as glutathione peroxidase, vitamin C, and vitamin E; to chelate a wide variety of metals that are associated with an increased production of free radicals; and to inhibit gene over-expression. Lipoic acid is a cofactor in the alpha-keto acid deyhdrogenase complex (KAD). It is attached via an amide linkage to lysine (lipoamide) within the KAD complex, and functions as a swing arm transferring substrates between active sites (Horton et al., 1996). Furthermore, lipoic acid also has the ability to stimulate the uptake of glucose in both muscle and adipose cells. Lipoic acid supplementation increased the rate of glucose uptake in adipose and muscle cells by 50% (Henrickens et al., 1994).; Due to the unique capabilities of lipoic acid, our objectives were to determine if supplementation of LA could prove beneficial to finishing cattle. Our first trial investigated the effect of lipoic acid supplementation on the growth performance and carcass merit of finishing beef, and on tenderness and retail display property of beef. The results of the trial indicated that lipoic acid supplementation provided no positive effect on growth performance, carcass merit, or retail display properties. However, lipoic acid supplementation did have a positive effect on beef tenderness.; Our second trial investigated the effects of lipoic acid supplementation on the immune response of viral-challenged steers. Supplementation of lipoic acid appeared to augment certain aspects of the immune function of steers facing a viral challenge. This augmentation was evidenced by decreased BW loss, increased DMI 7 d after viral challenge, and decreased acute phase response proteins associated with the inflammatory response of steers.; In conjunction with our first trial, we also evaluated the effects of limit-feeding finishing steers. The objectives of our study was to evaluate the effect of restriction dry matter intake of finishing steers 80% of ad libitum levels, while maintaining similar NE and MP compared to ad libitum fed cattle. The results of this study validate the findings of Linville et al. (2003), which reported that limit-feeding steers 80% of ad libitum while maintaining similar NE and MP results in increased growth performance while having no negative effect on carcass merit. Implementation of the limit-feeding management concept could prove to be a useful management technique. Limit-feeding can simplify bunk management (decrease labor), reduce feed cost (total pounds fed and decreased waste), and decreased fecal output.