Uso de alpeorujo en la alimentación de pollos broiler como aditivo fitogénico

The supplementation with antioxidants exerts positive effects both in improving productive parameters of animals and meat quality products. Vitamin E is included at high doses in commercial broilers feeds as antioxidant. The present study aims to evaluate an olive mill wastewater extract rich in hydroxytyrosol (HT), a powerful antioxidant, to spare or replace vitamin E (Vit E) as antioxidant in broiler feeds by analysing the oxidative stability of the breast meat. In addition, the effects of experimental diets on the expression of genes encoding antioxidant and homeostasis in muscle were studied. A total of 560 one-day-old Cobb 500 broiler were randomly distributed into 35 pens and fed with 5 treatments with 7 replicates of 16 chicks. Experimental diets contained corn and soybean meal as main ingredients and increasing concentrations of HT (0, 7.5, 15, 22.5 and 30 ppm) and decreasing concentrations of added vitamin E (40, 30, 20, 10, 0 ppm). After 39 days of feeding the experimental diets, birds were slaughtered and the breast muscle of seven broilers per treatment sampled. In meat samples, thiobarbituric acid reactive substances (TBARS) were evaluated to determine the effects of experimental diets on lipid oxidation on day 1, 3 and 7 of refrigerated (4 °C). Also, the expression of antioxidant systems genes (superoxide dismutase (SOD1), glutathione peroxidase (GPx1) and catalase (CAT)) and homeostasis maintenance genes (mechanistic target of rapamycin (mTOR) and hypoxia inducible factor 1 (HIF1)) were analysed at 4h and 24h post-mortem. The results showed a linear increase (P = 0.018) of lipid peroxidation after 3 days of storage with the progressive replacement of vitamin E with HT, being more relevant after 7 days (P < 0.0001) of storage. However, after a post-hoc analysis differences were only significant between meat samples of birds fed the 30 ppm of HT and the rest of dietary treatments who showed lower lipid peroxidation values. Statistical analysis did not reveal differences in the expression of the studied genes between treatments. However, compared to 4 h post-mortem the expression of CAT and GPx1 expression decreased (P < 0.0001; P = 0.005) and SOD1 and HIF1 tended to decrease (P = 0.069) at 24 h post-mortem. The expression of mTOR was not affected indicating its important role in homeostasis maintenance post-mortem. These findings suggest that using an olive mill wastewater extract including up to 22.5 ppm of HT could replace up to 30 ppm of vitamin E as antioxidant in broiler chicken feed without affecting lipid peroxidation in breast meat.