title: Alpha-tocopherol concentrations and case life of lamb muscle as influenced by concentrate or pasture finishing.
abstract: Two experiments were conducted to evaluate alpha-tocopherol accumulation in muscle of lambs finished on pasture or concentrates. The objective for Exp. 1 was to compare accumulation of alpha-tocopherol in the longissimus muscle of pasture-fed lambs to that of lambs fed three concentrations (15, 150, and 300 IU/kg of DM) of supplemental vitamin E (all rac alpha-tocopheryl acetate) in all-concentrate diets. The objective in Exp. 2 was to investigate the effect of duration of supplemental vitamin E feeding on alpha-tocopherol content and color change during display case storage of lamb muscle. Treatments evaluated in Exp. 2 were: 15 IU of supplemental vitamin E/kg DM fed to finish; 15 IU/kg followed by 300 IU/kg of DM during the last 21 d; and 15 IU/kg DM until 7 d prior to finish, then 300 IU/kg DM. In Exp. 1, alpha-tocopherol concentration of rotational grazed alfalfa and perennial ryegrass averaged 137 and 169 mg/kg of DM. Vitamin E treatments for lambs fed concentrate diets did not affect ADG (P > 0.15), but ADG was greater (P < 0.01) for concentrate-fed lambs than for grazing lambs. For the concentrate-fed lambs, alpha-tocopherol in longissimus muscle increased quadratically (P < 0.05) as dietary concentrations of vitamin E increased. Predicted maximum alpha-tocopherol concentration in muscle occurred at about 400 IU/kg of diet DM. Longissimus muscle from lambs grazing alfalfa or ryegrass had similar (P > 0.50) alpha-tocopherol concentrations, and those concentrations were similar to values obtained when the concentrate diet supplemented with 150 IU of vitamin E/kg was fed. In Exp. 2, no differences (P > 0.10) in ADG were observed. Concentrations of longissimus alpha-tocopherol were highest when 300 IU supplemental vitamin E was fed for 21 d prior to slaughter. During a 6-d display period, semimembranosus steaks from lambs fed 300 IU of supplemental vitamin E/kg for either 7 or 21 d had higher a* and b* color readings than steaks from lambs fed 15 IU/kg of supplemental vitamin E. Increased consumption of vitamin E either via pasture or supplementation results in higher alpha-tocopherol concentrations in meat.
authors.affiliation: Appalachian Farming Systems Research Center, USDA-ARS, Beaver, WV 25813, USA. kturner@afsrc.ars.usda.gov
authors.forename: K E
authors.initials: KE
authors.lastname: Turner
authors.forename: K E
authors.initials: KE
authors.lastname: McClure
authors.forename: W P
authors.initials: WP
authors.lastname: Weiss
authors.forename: R J
authors.initials: RJ
authors.lastname: Borton
authors.forename: J G
authors.initials: JG
authors.lastname: Foster
mesh_terms: D000821:Animal Feed; D000818:Animals; D003116:Color; D004305:Dose-Response Relationship, Drug; D005260:Female; D005511:Food Handling / Q000379:methods; D005519:Food Preservation / Q000379:methods*; D008297:Male; D008460:Meat / Q000032:analysis / Q000592:standards*; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism*; D010858:Pigmentation; D012756:Sheep / Q000254:growth & development / Q000378:metabolism*; D013997:Time Factors; D014018:Tissue Distribution; D024502:alpha-Tocopherol / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D024502:alpha-Tocopherol