Background: Although polyunsaturated fatty acids are in the spotlight due to their physiological effects on inflammation and stress of livestock animals, the biological roles of their derivatives, termed lipid mediators, have been little reported in laying hens.
Results: In this study, two hundred 33-week-old laying hens were fed 0, 0.9, 1.8, or 3.6% (w/w) dietary flaxseed (Lintex170) with a commercial basal diet for 4 weeks to determine the physiological effects of dietary flaxseed, an omega-3-rich ingredient, on host inflammation or stress states regarding lipid mediator profiles, and also its impact on laying performance. The physiological changes in the omega-6 to omega-3 ratio, lipid mediator profiles, serum proinflammatory cytokine (tumor necrosis factor-alpha, interleukin-1beta, interleukin-6) levels, serum corticosterone levels, and the ratio of heterophils to lymphocytes were monitored. Supplementing dietary flaxseed greatly reduced the omega-6 to omega-3 fatty acid ratio from 25.85 to 4.16 in eggs and from 19.23 to 4.08 in serum samples between groups fed with 0% and 3.6% dietary flaxseed after the experimental period. In addition, the lipid mediator profiles of laying hens were modulated by supplementation with flaxseed, mainly resulting in enrichment of omega-3 fatty acid-derived lipid mediators. Furthermore, the level of proinflammatory cytokines TNF-alpha decreased when fed 3.6% (w/w) dietary flaxseed. Two stress indices, corticosterone in the serum and the heterophil to lymphocyte ratio showed significant reductions in laying hens fed 3.6% (w/w) dietary flaxseed. Additionally, overall laying performance indices were significantly improved by supplementary flaxseed.
Conclusion: Taken together, these findings suggest that the decreased omega-6 to omega-3 ratio and enrichment of omega-3-derived lipid mediators induced by dietary flaxseed may contribute to reducing the stress state in laying hens, improving laying performance. These findings broaden the understanding of lipid mediator profiles in laying hens, and the results will be applied to develop antiinflammatory and antistress feed additives for the poultry industry.