Effect of supplementation of a phytogenic feed additive in the diet of laying hens on nutritional quality of eggs

The present study aimed to determine the effects of supplementing a phytogenic feed additive (PFA) in the diet of laying hens on egg quality and shelf life. The experiment was conducted on sixty 32weeks old TETRA SL laying hens assigned to two dietary treatments, 30 birds each. Each treatment was replicated ten times with three chicks per replicate pen. Dietary treatments included feeding a control corn-soybean diet (CON) alone and the same supplemented with a phytoadditive supplement (PFA) at 1% level. The PFA contained sea buckthorn meal (50%), walnut leaves (25%) and bilberry leaves (25%) as an important contributor to vitamin E, lutein and zeaxanthin concentrations in experimental compound feed. The inclusion of the PFA in laying hens diets led to the accumulation of nutrients with antioxidant potential in the egg yolk, namely, lutein and zeaxanthin (11.32 vs. 9.38 mg/kg in PFA and CON groups, respectively; P=0.007) and zinc (82.24 mg/kg for PFA vs. 78.98 mg/kg for CON; P=0.002) in egg yolk. The oxidative stability parameters of eggs, namely peroxide value (PV), conjugated dienes-(CD) and trienes (CT), p-anisidine value and thiobarbituric acid-reactive substances (TBARS), were decreased significantly for both primary (PV, CD, CT) and secondary oxidation products formed in eggs yolks of experimental groups, proving an efficient inhibition effect of lipid peroxidation process. The TBARS values were significantly (P=0.04) reduced in the PFA (0.123 mg/kg) than CON (0.148 mg/kg) group. It is concluded that the PFA inclusion in laying hens diets improved the antioxidant status of egg yolk, and the lipid peroxidation process during storage was delayed.