Comparisons of BHT and Ethoxyquin as Antioxidants in the Nutrition of Broilers

BHT and ethoxyquin (EQ) at a level of 125 mg./kg. protected with equal effectiveness lipid components in practical-type and semi-purified diets held during period of 27 weeks at temperatures which ranged from 18°C. to 26°C. These antioxidants acted similarly in improving body weights, feed/gain ratio and liver vitamin A, but only when tested under conditions which led to deterioration of unprotected diets. EQ as well as BHT increased the accumulation of xanthophylls in livers of chicks, this effect being greater than expected from their stabilization of dietary xanthophylls. EQ significantly improved the stability of liver lipids (TBA values) as compared with the unsupplemented control, but not as compared with BHT. TBA values were also significantly affected by α-tocopheryl acetate and the quality of the dietary oil. EQ, but not BHT, at levels of 80 and 120 mg./kg., almost completely prevented encephalomalacia in chicks fed a semi-purified diet low in vitamin E, and containing oxidized safflower oil. Results of this study indicate that under practical conditions neither antioxidant showed a clear superiority over the other.