Enhancing the nutritional values of egg yolks of laying hens by different dietary sources of omega-3 fatty acids, vitamin e and trace elements

• Dietary whole flaxseed, fish oil and vitamin E with organic form of Se, Zn, and Fe had a positive effect on antioxidative properties in blood and egg. • Dietary whole flaxseed, fish oil and vitamin E with nano form of Se, Zn, and Fe improved the egg yolk lipids, fatty acids profile, and health indices. The present study aims to investigate the effect of whole flaxseed (WFS), fish oil (FO), and different sources of Se, Zn, and Fe on lipid metabolites, antioxidant status, immunity, egg yolks’ minerals (Se, Zn and Fe) and fatty acids and eggs’ lipid and health index in laying hens. A total of 144 hens were divided into 6 groups with 6 replicated of 4 hens each. The laying hens were fed diets containing 0, 7.5 % whole flaxseed (WFS)+1.5 % fish oil (FO), 7.5 %WFS+1.5 % FO+175 mg kg -1 vitamin E (VE), 7.5 %WFS+1.5 % FO+ 175 mg kg -1 VE +inorganic sources of Se, Zn, and Fe (ISeZnFe), 7.5 %WFS+1.5 % FO+175 mg kg -1 VE+ organic sources of Se, Zn, and Fe (OSeZnFe) and 7.5 %WFS+1.5 % FO+ 175 mg kg -1 VE +nano-source of Se, Zn, and Fe (NSeZnFe) from 40 to 50 weeks of age. Results clarified that incorporation of 7.5 %WFS+1.5 %FO+VE+OSeZnFe or 7.5 %WFS+1.5 %FO+VE+NSeZnFe increased serum concentration of HDL-cholesterol and HDL/LDL ratio, while reduced LDL-cholesterol and the hypercholesteremia index (RHCH) in comparison with control. Dietary 7.5 %WFS+1.5 %FO+VE+OSeZnFe or 7.5 %WFS+1.5 %FO+VE+NSeZnFe increased concentrations of total antioxidants capacity and vitamin E and reduced concentrations of malonaldehyde (MDA) in blood serum and egg contents. Interestingly, dietary inclusion of 7.5 %WFS+1.5 %FO+VE+OSeZnFe, or 7.5 %WFS+1.5 %FO+VE+NSeZnFe increased α-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), and total n-3 PUFAs concentrations in egg yolk, while reduced arachidonic acid (ARA) in the egg yolks, whereas n-6/n-3 PUFAs ratio was decreased significantly. Moreover, incorporation of 7.5 %WFS+1.5 %FO+VE+OSeZnFe, or 7.5 %WFS+1.5 %FO+VE+NSeZnFe improved egg health indices. It might be concluded that, inclusion of 7.5 %WFS+1.5 %FO+VE+OSeZnFe, or 7.5 %WFS+1.5 %FO+VE+NSeZnFe in hens’ diets had a positive effect on antioxidative properties in blood serum and eggs yolks contents; at the same time, it improved the egg yolk lipids, fatty acids and its related health and nutritional indices.