The effects of dietary β-glucan supplementation on performance and immune response of broiler chicks during an Eimeria challenge

Escalating consumer concerns have placed the poultry industry under mounting pressure to reduce the use of chemotherapeutic agents as feed additives. One possible alternative receiving increased attention is the use of immunomodulators such as β-glucan. A pilot study evaluated the effects of a yeast derived β-glucan (Auxoferm YGT) on growth performance and immune response of broiler chickens. Day-old chicks were fed a diet containing 0, 0.02, or 0.1% yeast β-glucan. On days 7 and 14 post-hatch, body weight and relative immune organ weights were measured, peripheral blood was collected to determine heterophil to lymphocyte (H:L) ratios, and small intestinal sections were sampled to evaluate relative gene expression. The addition of β-glucan had no influence on growth. Dietary β-glucan supplementation modulated the expression of interleukin (IL)-8, IL-18, interferon (IFN)-γ and inducible nitric oxide synthase (iNOS) in the small intestine. A subsequent study was conducted to investigate the effects of dietary β-glucan on broiler chick (1440 birds) performance and immune response during a mixed Eimeria infection (day 8 of age). Measurements were taken and samples collected on days 4, 7, 10, 14 and 21 post-hatch. The results from this study show that β-glucan supplementation did not negatively impact performance. The addition of β-glucan to the diet resulted in reduced gross lesion severity and increased H:L ratios. The gene expression results suggest that β-glucans are capable of skewing the host immune response toward aTh1 mediated response and consequently down-regulating the Th2 mediated response.