An extra-virgin olive oil rich in polyphenolic compounds has antioxidant effects in meat-type broiler chickens.

The aim of this study was to extend the knowledge on the antioxidant effect of extra-virgin olive oil (EVOO) in the liver of broiler chickens not subjected to any form of insult. A total of 120 male broiler chickens (Hubbard strain) were divided into three groups and fed ad libitum with three isoenergetic diets from hatching until slaughter age (49 days) on a completely randomized design. The dietary treatments consisted of 2.5% added oil or fat from three sources as follows: diet containing sunflower oil (SFO); diet containing lard (LRD), and diet containing extra-virgin olive oil (EVOO). The activity of the main antioxidative enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GS-Px) and glutathione S-transferase (GST), and lipid peroxidation as thiobarbituric acid-reactive substances (TBARS) content, was measured in the liver of chickens. The susceptibility to undergo lipid peroxidation was assessed by exposing liver homogenate to 30 °C or to an ascorbate/iron mixture as pro-oxidant system. Dietary oil or fat type improved significantly (P < 0.05) the body weight and gain as well as feed efficiency in birds fed EVOO compared to those fed with the other treatments. Supplementing EVOO in the diet significantly (P < 0.05) reduced lipid peroxidation by increasing antioxidant defense system. These findings, besides adding more results on the antioxidant effect of extra-virgin olive oil on liver of other experimental model other than rats and humans, could be significant for animal welfare, with consequent benefits for both producers and consumers.