This study examined dose-response effects of supplemental dietary dl-α-tocopheryl acetate (VE) on growth performance, immune response, and carcass and meat sensory characteristics in two breeds of cattle. Seventy-five crossbred beef steers (361 ± 22 kg) were blocked by weight, randomly assigned to one of five treatment groups, and fed a ration supplemented with 0, 250, 500, 1000 or 2000 IU VE steer−1 d−1. Sixty Holstein steers (366 ± 22 kg were similarly blocked and allocated (no 250 IU treatment). Four days post-slaughter the left sirloin subprimal of each steer was removed and vacuum packaged. On day 13, small cores were cut from the gluteus medius (GM) and packaged with O2-permeable wrap; these were then displayed under 45-W natural white light for up to 10 d at 4 °C. Serum α-tocopherol increased (P < 0.0001) with increasing VE in both breeds, although more so (P < 0.0001) in beef steers. The GM α-tocopherol levels increased linearly (P < 0.0001) with increasing VE, but more so (P < 0.0002) in beef steers. The levels of α-tocopherol in semimembranosus muscle, perirenal and subcutaneous fat, and liver also increased linearly (P < 0.0001) in both breeds. Growth performance of all steers and carcass characteristics of beef steers were not affected (P > 0.10) by VE. Dairy steers receiving 1000 IU d−1 had darker (P < 0.03) ribeyes. There were no effects (P > 0.10) of VE on sensory attributes of frozen steaks. Surface metmyoglobin formation was deterred by VE supplementation in meat from beef (linear, P < 0.016) but not dairy (P > 0.10) steers. Lipid oxidation was suppressed (linear, P < 0.0002) by VE but more so (P < 0.0001) in beef than in dairy meat (72.9% vs. 40.0% suppression, respectively, at 2000 IU d−1). Immune response increased (P < 0.074) at higher levels of VE. In summary, VE supplementation improved immune response and increased serum and muscle α-tocopherol levels, resulting in delayed metmyoglobin formation (beef) and lipid oxidation (beef and dairy) in a dose-dependent manner. Supplemental VE was more effective in meat from beef steers than in that from dairy steers. Key words: Vitamin E, immunity, growth, carcass
282 Impact of dietary peroxidized lipids and antioxidant supplementation in feed on growth performance and oxidative status of newly weaned piglets
