Effect of alpha tocopherol acetate and ascorbic acid on performance, carcass traits and incidence and severity of liver abscesses in feedlot cattle.

Liver abscesses (LA) in cattle negatively affect feedlot performance by decreasing ADG, feed intake, and G:F ratio. Abscessed livers are condemned and abdominal adhesions associated with LA can result in extensive carcass trimming during harvest, further compounding adverse economic impact. Given regulatory changes pertaining to the use of in-feed antibiotics in cattle production, there is growing interest in alternatives to antibiotics for LA control. The objective of this study was to evaluate the use of antioxidants, crystalline ascorbate and alpha tocopherol acetate, for mitigation of LA in feedlot cattle. Yearling crossbred heifers (n=392; initial BW 481 ± 9.4 kg) were blocked by previous treatment and allocated randomly to 24 dirt-surfaced feedlot pens (10 m x 35 m) with 14 heifers/pen. Heifers were weighed, implanted with Component® TE-200 implants, and placed into feeding pens. Finishing diets consisted of 60% steam-flaked corn, 30% wet corn gluten feed, 8% alfalfa, and 2% supplement (DM basis) that provided 300 mg/d monensin, and either 200 IU/d alpha tocopherol acetate (CTL) or 2000 IU/d alpha tocopherol acetate plus 500 mg/d crystalline ascorbate (AOX). Heifers were fed once daily ad libitum for 94 d, then weighed and transported 450 km to a commercial abattoir for harvest. Hot carcass weight and incidence/severity of LA were determined the day of harvest, and carcass traits were evaluated following 36 h of refrigeration. Compared to CTL, feeding AOX tended to decrease DMI (10.66 vs. 10.31 kg/d; P = 0.08) and improve G:F (0.1204 vs. 0.1254; P = 0.12), but did not impact ADG, incidence of LA (25.6 vs 23.5% for CTL and AOX, respectively), HCW (828.4 vs 830.5 kg for CTL and AOX, respectively), or other carcass traits (P>0.20). In conclusion, feeding antioxidants is not a viable alternative to decrease incidence of liver abscesses in finishing cattle.