Effect of vitamin E supplementation on alpha-tocopherol and beta-carotene concentrations in tissues from pasture- and grain-fed cattle

YANG A., BREWSTER M. J; LANARI M.C.; Y TUME R.K.

MEAT SCIENCE

Año: 2002 p. 35 - 40

0309-1740

The effects of dietary vitamin E supplementation of grain-fed cattle on lipid oxidation and meat colour have been extensively investigated, but little attention has been given to pasture-fed cattle where meat is likely to contain naturally high amounts of alpha -tocopherol and carotenoids. In the work described, the effects of pasture-feeding alone and with vitamin E supplementation on tissue levels of antioxidants were evaluated; the findings were compared with those obtained for grain-fed cattle with and without supplementation. Sorghum was the major component of the grain-based ration. alpha -Tocopherol concentrations in plasma, muscle and fat tissues of pasture-fed cattle were not affected by vitamin E supplementation (2500 IU/head/day for 132 days prior to slaughter), whereas those of grain-fed cattle increased significantly. The alpha -tocopherol concentrations in muscle and liver of supplemented grain-fed cattle were similar to those for pasture-fed animals but were lower in fat (P<0.05). The major carotenoid present in all tissues studied from pasture-fed animals was beta -carotene, and its contents in plasma, liver, fat and muscles were decreased (P<0.05) by supplementation with vitamin E. Carotenoids were essentially absent in grain-fed cattle except for small amounts in liver. The implication of this study for the meat industry is that cattle grazed on good pasture can achieve concentrations of alpha -tocopherol in muscles and other tissues, at least as high as those obtained by supranutritional supplementation of grain-fed cattle with vitamin E. However, alpha -tocopherol supplementation of pasture-fed cattle reduced tissue concentrations of beta -carotene, which would reduce carcass fat yellowness and make pasture-fed cattle more acceptable to some Asian markets.