Egg Production and Quality, Lipid Metabolites, Antioxidant Status and Immune Response of Laying Hens Fed Diets with Various Levels of Soaked Flax Seed Meal

Flax seed meal is a valuable source of fatty acids, particularly omega-3 such as alpha-linolenic acid (ALA), but its mucilage contents limit its use. This study assessed the effect of different levels of soaked flax seed meal (SFSM) on the production and health parameters in Rhode Island Red laying hens. A total of 120 hens were divided into three groups and fed diets containing 0, 6, and 12% SFSM for 10 weeks. The impact was determined based on the egg production and quality, lipid metabolites, antioxidant status, immune response, fertility, and hatchability. Diets containing up to 12% SFSM had no adverse effects on the laying rate, egg weight and mass, and feed conversion ratio (FCR). Hens supplemented with a diet containing 12% SFSM exhibited an improved egg-specific gravity, shell thickness, and yolk color. Moreover, egg albumen (%) and blood and meat spots were significantly increased. The Haugh unit score decreased substantially in chickens supplemented with a diet containing 12% SFSM. Moreover, the blood plasma and yolk lipid profiles were significantly reduced dose-dependently. The inclusion of SFSM improved the yolk lipoprotein by increasing the plasma and yolk high- density lipoprotein (HDL) and HDL/LDL (low-density lipoprotein). However, the antioxidant markers, namely, malondialdehyde (MDA), and the ratio between total antioxidants capacity (TAC)/MDA, were negatively affected in hens fed a 12% SFSM diet. Furthermore, the birds fed a 12% SFSM diet had a better immune response based on the phagocytic activity, phagocytic index, lymphocyte transformation test, lysozyme activity, and antibody titer for Newcastle disease virus. The fertility and hatchability increased significantly by 4.81 and 6.74%, respectively, when the hens were fed a diet of 12% SFSM compared with the control. In conclusion, up to 12% of SFSM in hens’ diets had no adverse effects on the productive and reproductive performances; at the same time, they improved the yolk color, plasma lipid profiles, yolk lipid profiles, and immune parameters.