Influence of supplementing corn-soybean meal diets with vitamin E on performance and selected physiological traits of male turkeys

Department of Animal Science, Iowa State University, Ames 50011-3150, USA.

Three experiments were conducted to determine the effects of supplementing practical diets of male turkeys with dl-alpha-tocopheryl acetate (TA). In Experiment 1, a factorial arrangement of dietary treatments [0, 12, 50, 150, and 300 IU TA/kg with 0 or 300 mg ascorbic acid (AA)/kg] was used. These 10 treatments were fed to poults from 1 to 41 d of age. From 41 to 118 d of age, the AA treatments were discontinued, and the 300 IU TA treatment groups were changed to 12 IU TA/kg. Neither TA nor AA treatments affected 41-d BW, feed to gain ratio (FE), or livability. No effects of dietary TA concentrations on turkey performance were observed through 118 d of age alpha-Tocopherol (TOC) concentrations of plasmas and livers were increased by increments of dietary TA, with substantial liver storage when toms were fed 150 IU TA/kg from 1 to 118 d. Supplementing diets with 0, 25, 50, 75, or 100 IU TA/ kg in Experiments 2 and 3 had no effect on performance of toms through 119 and 105 d, respectively. alpha-Tocopherol concentrations of plasma and red blood cells (RBC) increased linearly with increments of dietary TA. The same was true for livers in Experiment 2. Susceptibility of RBC to hemolysis induced by 400 microM t-butyl hydroperoxide (TBH) in Experiment 2 decreased with increasing dietary TA, and these decreases corresponded to increases in TOC concentration of RBC. However, the relationships between hemolysis and dietary TA or RBC TOC were inconsistent in Experiment 3 and varied according to concentration of TBH (200, 300, or 400 microM) and age of the toms. At 105 d of age, RBC of toms fed no supplemental TA were resistant to hemolysis, irrespective of dietary TA and TBH concentration. In Experiment 3, there were no indications of dietary TA effects on plasma peroxide concentration or activity of plasma creatine kinase. A positive relationship between dietary TA and blastogenic responses of blood lymphocytes was observed with concanavalin A when toms were at 44 d but not at 23 or 86 d of age. The overall data indicate that corn-soybean meal diets containing from 6 to 20 IU TOC/kg, but no supplemental TA supported satisfactory performance and well-being of male turkeys from 1 d of age to market ages when the turkeys were free of disease, as was true in the research reported here.

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