Effect of dietary oregano essential oil on performance of chickens and on iron-induced lipid oxidation of breast, thigh and abdominal fat tissues.

1. We studied the effect of dietary oregano essential oil (50 and 100 mg/kg of feed) on the performance of broilers, and determined the susceptibility of the resulting broiler meat to iron-induced lipid oxidation. 2. Performance of the birds was unaffected by the experimental diets. Therefore, dietary oregano oil exerted no growth-promoting effect on broilers. 3. Iron-induced lipid oxidation showed that as oregano oil increased in the diet, malondialdehyde values decreased in tissue samples, suggesting that the oil, particularly at 100 mg/kg of feed, exerted an antioxidant effect on chicken tissues. 4. Dietary alpha-tocopheryl acetate supplementation at 200 mg/kg of feed displayed greater antioxidant activity than oregano oil at either supplementation rate. 5. Thigh muscle was more susceptible to oxidation than breast muscle, although the former contained alpha-tocopherol at higher concentration. Muscle alpha-tocopherol is an important factor influencing lipid oxidation, but the influence of polyunsaturated fatty acids and content of pro-oxidants must be taken into consideration too.