A major goal of many poultry producers is to attain good flock liveability. Historically, most poultry producers have manipulated environmental conditions and management to maximize bird health. In the past two decades there has been much research into nutritional regimes that improve bird health through immunomodulation. Commercial poultry environments contain ubiquitous micro-organisms that continuously challenge the immune system. Nutritional supplements that enhance immune system function may improve flock performance and be economically advantageous. This paper reviews the literature on zinc-methionine and the avian cellular immune system. Current knowledge of the effects of zinc on many animal models is reviewed and a hypothetical mechanism for the action of zinc-methionine on this system is discussed. The role of metals in the production of toxic oxygen metabolites by mononuclear phagocytes. in: Nutrient Modulation of the Immune Response (Ed. Cunningham-Rundles, S.), Marcel Dekker Inc, New York, pp.127-140 CORRIER, D.E. and DELOACH, J.R. (1990) Evaluation of cell-mediated, cutaneous basophil hypersensitivity in young chickens by an interdigital skin test. Poultry Science 69: 403-408 COUSINS, R.J. (1985) Absorption, transport and hepatic metabolism of copper and zinc: Special reference to metallothionine and ceruloplasmin.

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Beta-1,3/1,6-glucan (beta-glucan) was tested as a possible immunomodulator. Chicken macrophages from a macrophage cell line MQ-NCSU and from abdominal exudate of broiler chickens were exposed to various concentrations of beta-glucan in vitro. In addition, day-old broiler chicks were fed a diet containing 0, 20, and 40 mg/kg beta-glucan in the starter and 0, 20, and 20 mg/kg in the grower diet. Several baseline immune parameters were examined following such exposures. The results showed that beta-glucan exposure increased nitrite and interleukin-1 (IL-1) production as well as induced macrophage to proliferate in culture. However, IL-6 production was not affected. Dietary beta-glucan supplementation increased the macrophage phagocytic activity, anti-sheep red blood cells antibody response post-boost, as well as the PHAP-mediated lymphoproliferative response measured as a toe-web swelling. The percentage of CD4+, CD8+, and CD4+/CD8+ double positive lymphocytes in the intestinal intraepithelial leukocytes was increased in beta-glucan supplemented chicks. Furthermore, the primary and secondary lymphoid organs such as bursa of Fabricius, thymus and spleen were larger in beta-glucan-supplemented chicks as compared to the chicks on basal diet. The findings of these studies which showed that beta-glucan improves several baseline immune responses in the chicken imply that beta-glucan can be used as a possible immunomodulator in food animals such as the chicken.

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