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Poult Sci. 2010 Sep;89(9):1924-33. doi: 10.3382/ps.2010-00865.

Performance and immune responses to dietary beta-glucan in broiler chicks.

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Avian Immunobiology Laboratory, Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA, USA.


During the first week posthatch, the avian immune system is immature and inefficient at protecting chicks from invading pathogens. Among immunomodulators, beta-glucans are known as biological response modifiers due to their ability to activate the immune system. Current research suggests that beta-glucans may enhance avian immunity; however, very little is known about their influence on regulation of immune function. A study was performed to evaluate the effects of dietary beta-glucan on growth performance, immune organ weights, peripheral blood cell profiles, and immune-related gene expression in the intestine. One-day-old chicks were fed a diet containing 0, 0.02, or 0.1% yeast beta-glucan (n = 30/treatment). On d 7 and 14 posthatch, body and relative immune organ weights were measured and small intestinal sections were collected to evaluate gene expression by quantitative real-time PCR. Peripheral blood samples were also collected to determine heterophil:lymphocyte ratios. Supplementation of beta-glucan did not significantly affect BW gains, and no significant differences were observed among groups for relative immune organ weights or heterophil:lymphocyte ratios. Compared with controls, expression of interleukin (IL)-8 was downregulated in the beta-glucan-treated groups on d 7 and 14. On d 14, beta-glucan inclusion resulted in increased inducible nitric oxide synthase expression. Expression of IL-18 was upregulated on d 7 but reduced on d 14 due to beta-glucan supplementation. On d 7, interferon-gamma and IL-4 expression decreased in the beta-glucan-treated groups. However, on d 14, IL-4 expression was upregulated in the supplemented groups. Intestinal expression of IL-13 was also downregulated in the beta-glucan-treated birds on d 7. These results suggest that dietary inclusion of beta-glucans altered the cytokine-chemokine balance; however, it did not elicit a robust immune response in the absence of a challenge, resulting in no deleterious effects on performance.

[Indexed for MEDLINE]

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