Fortification of rabbit diets with vitamin E or selenium affects growth performance, lipid peroxidation, oxidative status and immune response in growing rabbits

The objective of the present study was to examine the effects of supplemental dietary vitamin E (vit. E), organic selenium (Se) or vit. E+Se on growth performance, carcass characteristics, lipid peroxidation, antioxidative status and immune response in growing rabbits and to investigate their potential synergism on storage stability of rabbit meat. A total of 80 six weeks old male Californian rabbits were randomly divided into four experimental treatments (20 each): (1) control (basal diet without any supplementation of vit. E or Se); (2) vit. E (basal diet +250 mg α-tocopherol acetate/kg diet); (3) Se (basal diet+0.3 mg organic Se/kg diet); and (4) vit. E+Se (basal diet +250 mg α-tocopherol acetate/kg diet+0.3 mg organic Se/kg diet). All experimental treatments were provided from 6 to 12 weeks of age. Animals were provided with feed and water ad lib. Supplemental dietary vit. E, organic Se and vit. E+Se increased the final body weight, daily gain, hot carcass weight and dressing percentage, while feed conversion ratio was reduced in the growing rabbits. Dietary supplementation with vit. E and organic Se increased the content of vit. E and Se in raw rabbit meat by more than three- to five-folds, respectively (P≤0.05). Interestingly, dietary treatments decreased the index of lipid oxidation (thiobarbituric acid reactive substance, TBARS, values) in raw meat at 1, 3 and 6 days post mortem (P≤0.05). Also, the inclusion of vit. E plus organic Se in the rabbit diet markedly enhanced the serum glutathione peroxidase (GSH-Px) activity and total antioxidant capacity significantly being three times greater than the corresponding value of controls and, simultaneously, reduced the TBARS concentration in plasma to about 19% of the controls. The inclusion of vit. E, Se, or vit. E+Se in the growing rabbits' diets improved the humoral immune response compared to the controls (P≤0.05). Serum total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides, total protein and albumen were not significantly affected by dietary treatments while serum globulins were significantly elevated. In conclusion, supplemental dietary vit. E, Se, or vit. E+Se enhanced growth performance, vit. E and Se content in raw meat, meat oxidative stability, serum antioxidative status and immune responsiveness in growing rabbits.