Effects of flaxseed lignans on laying hen reproductive parameters

Abstract

Flaxseed, rich in the essential omega-3 fatty acid (FA) linolenic acid (LNA; C18:3n-3), can be included in laying hen rations for the production of omega-3 FAenriched shell eggs. In addition to being a rich source of LNA, flaxseed is also the most abundant food source of the plant lignans secoisolariciresinol-diglycoside (SDG) and matairesinol, which serve as precursors for the bacterial synthesis of lignans in mammals. Lignans are known to possess weak estrogenic/antiestrogenic characteristics due to their structural similarity to endogenous estrogens. In the current study, dietary flaxseed (I 5%) was included in poultry rations to evaluate the influence of flaxseed on the reproductive performance and health of 18 to 28-week-old laying hens. Serum estradiol concentrations, body, liver, reproductive organ weights, and follicular (Fl to F5) weights and diameters, were determined during regular sample periods. Changes in reproductive organ characteristics were accompanied by a significant reduction in circulating estradiol in response to 15% dietary flaxseed, suggesting that flaxseed lignans may influence the avian endocrine environment. Although many studies have confirmed the bacterial synthesis of lignans in mammals, these phytocheniicals have never before been studied in a non-mammalian model. A further study was conducted to determine-nine the capability of the hen cecal microflora to convert SDG and matairesinol to lignan compounds. The production of "avian lignans" was verified in vitro after exposing pullet cecal microflora to the lignan precursors of flaxseed. As the SDG content, and therefore lignan production capability, varies between cultivars, different strains namely Flanders (low SDG/high LNA) and Linola 947 TM (high SDG/low LNA) were evaluated for their influence on laying hen estradiol. Reductions in serum estradiol were not observed as in earlier experiments, indicating that another mechanism may also play a role in the hormonal modulation in young laying hens. In conclusion, dietary flaxseed may influence the avian endocrine environment and thus laying hen reproductive parameters. This influence may impact production consistency in the egg industry. It is possible that this effect may be circumvented by supplementing diets with a lower level of a flaxseed or by using reproductively mature hens.