Effect of dietary wine lees on oxidative stress, egg quality and yolk lipid stability in laying hens fed with a diet rich in n-3 polyunsaturated fats

Wine lees (WLs) are a by-product of the winemaking process, but the valorization of WLs as poultry feed has not yet been achieved. Accordingly, the aim of the present study was to evaluate the potential benefits of using WLs as a feed ingredient. To this end, we investigated their effects on serum and hepatic markers of oxidative stress and egg quality in laying hens susceptible to lipid peroxidation by feeding them diets enriched in n-3 PUFA. In addition, lipid profile and oxidative stability of the yolk during storage were evaluated. A total of 128 30-week-old Tetra SL laying hens were divided into four groups (n = 32): the negative control (C–) received a standard diet, while the three other groups (positive control, C+; WL2.5; and WL5) received the standard diet supplemented with 5 % linseed oil rich in n-3 PUFA. In the WL2.5 and WL5 groups, WLs were introduced into the diet at levels of 2.5 % and 5 %, respectively. The increased intake of n-3 PUFA induced oxidative stress, which was evidenced by increased malondialdehyde (MDA) and reduced serum and liver antioxidant enzyme activity. However, these parameters were significantly improved in hens supplemented with WLs. The reduction in n-3 PUFA content in stored eggs was < 19 % in hens fed with WLs, while the reduction exceeded 33 % in the C+ group. In conclusion, WLs can improve egg production and egg quality (yolk color and cholesterol content), the antioxidant status of hens and the oxidative stability of eggs, with the possibility of extending their shelf life.