Effect of different vitamin E sources and levels on selected oxidative status indices in blood and tissues as well as on rearing performance of slaughter turkey hens

Abstract

SUMMARY The experiment was carried out with 600 turkey hens of the Big 6 line aged from 1 to 16 wk. The birds were assigned to 5 experimental groups. The factors differentiating the groups were the chemical form and level of a tocopherol (vitamin E) precursor administered as a feed additive ( dl -α-tocopherol acetate-E 307, according to the European Union Register of Feed Additives). The following 5 dietary treatments were used: group 1 (control): synthetic dl -α-tocopherol acetate at a dietary inclusion level of 50 mg/kg (1 to 9 wk of age) and 45 mg/kg (10 to 16 wk of age), being close to the vitamin E level recommended for SPF (standards poultry feeding) turkey hens in 2005; groups 2 and 3: the same form of vitamin E precursor (as in group 1) added to the diet but at 2-fold (group 2) and 3-fold (group 3) increased doses as compared with the control; and groups 4 and 5: a different form of supplemental vitamin E, natural RRR- d -α-tocopherol, at a 2-fold lower dietary inclusion level (group 4) and a comparable level (group 5) compared with the control. The turkey hens fed the synthetic dl -α-tocopherol acetate feed additive (group 2 and 3) were characterized by significantly higher performance than the control birds, yet were comparable with the groups fed the natural form of RRR- d -α-tocopherol additive (groups 4 and 5). The birds receiving the natural form of RRR- d -α-tocopherol showed a higher dressing percentage and a lower abdominal fat level as compared with the group with the highest dose of synthetic dl -α-tocopherol acetate. It was found that the supplemental natural form of RRR- d -α-tocopherol applied at the 2-fold lower dietary inclusion level or comparable with the dl -α-tocopherol acetate recommended in 2005 for SPF turkeys stimulated the antioxidant status of the body significantly better than the synthetic tocopherol acetate and, consequently, played a more efficient antioxidative role in the organism.