|Turner, Kenneth - Ken|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/2002
Publication Date: 10/1/2002
Citation: TURNER, K.E., MCCLURE, K.E., WEISS, W.P., BORTON, R.J., FOSTER, J.G. ALPHA-TOCOPHEROL CONCENTRATIONS AND CASE LIFE OF LAMB MUSCLE AS INFLUENCED BY CONCENTRATE OR PASTURE FINISHING. JOURNAL OF ANIMAL SCIENCE. 2002. v. 80(10). p. 2513-2521. Interpretive Summary: High concentrations of vitamin E in lean muscle can delay the development of an undesirable brown color of meat cuts during retail display. Supplementation of vitamin E to livestock finishing diets can be expensive. Forages naturally contain high concentrations of vitamin E. We compared finishing lambs on grazed forage to finishing lambs in feedlot fed high levels of vitamin E on the accumulation of vitamin E in carcass lean and evaluated color change and shelf life of meat retail cuts. Finishing lambs on alfalfa or perennial ryegrass pastures can result in vitamin E intakes 10x higher than National Research Council recommendations without negatively impacting performance. Feeding concentrate diets containing 10x or 20x National Research Council vitamin E recommendations for just 21 or 7 days prior to slaughter can increase vitamin E levels in lean tissue resulting in less lean discoloration over time, extended shelf life, and higher overall acceptance of retail cuts by consumers. This work is important to farmers, as pasture finishing offers multiple economic benefits of reduced feed costs of forage-based rations and rations containing naturally high levels of vitamin E compared to the more expensive concentrate, vitamin E supplemented rations.
Technical Abstract: In Exp. 1, alpha-tocopherol concentration in lean from lamb finished on grazed alfalfa (Medicago sativa L.; ALF) or perennial ryegrass (Lolium perenne L.; RG) pasture was compared with lean concentration from lambs supplemented with vitamin E (all rac alpha-tocopheryl acetate) in all- concentrate diets offered in drylot (DL). Vitamin E concentrations (IU/kg DM) in lamb DL diets were formulated to contain: NRC, 15; 10x NRC, 150; and 20x NRC, 300. Averaged over the finishing period, alpha-tocopherol concentration in herbage was 137 and 169 æg/g for ALF and RG, respectively. For DL lambs, alpha-tocopherol concentration in loin muscle was linearly related to the natural logarithm (Ln) of the dietary vitamin E concentration (muscle alpha-tocopherol, æg/g = -2.82 + 1.189 x Ln dietary vitamin E, mg/kg, P < 0.01, r2 = -0.97; RMSE = 0.29). Loin alpha- tocopherol concentrations were similar when lambs grazed ALF or RG or were fed the 10x NRC diet in DL. In Exp. 2, loin alpha-tocopherol concentrations were highest when 300 IU/kg DM was offered to lambs 7 or 21 d prior to slaughter compared to control lambs receiving 15 IU/kg DM for the length of the finishing period. On d 3, loin chop lean color from lambs offered 300 IU vitamin E 21 d prior to slaughter was higher (P < .05) compared to control lambs fed 15 IU vitamin E and lambs fed 300 IU vitamin E 7 d prior to slaughter. In general, vitamin E supplementation (20 x NRC) for 7 or 21 d prior to slaughter resulted in less leg steak and loin chop discoloration and higher overall acceptance by an consumer-based evaluation panel.