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OmniGen-AF and OmniGen Pro improve immunocompetence of ewes subjected to dexamethasone-induced immunosuppression.

M. Garcia



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OmniGen-AF and OmniGen Pro improve immunocompetence of ewes subjected to dexamethasone-induced immunosuppression.
M. Garcia*, H. A. Roberts, S. A. Armstrong, J. D. Chapman, D. J. McLean. Phibro Animal Health Corporation Teaneck, NJ.

OmniGen-AF (OGAF; Phibro Animal Health, Teaneck, NJ) is a feed additive with demonstrated benefit on improving cellular immunocompetence of stressed animals. OmniGen Pro (OGPRO, Phibro Animal Health) is a new product built on the OmniGen foundation, developed to maintain the principles of OGAF while improving gastrointestinal tract function and integrity. This study aimed to confirm the similar immunological effects of these 2 products. Fifteen Dorset ewes (39 kg BW) were randomly assigned to 1 of 3 diets: control (no additive), OGAF (6 g OGAF/head/d), and OGPRO (6.75 g OGPRO/head/d). Ewes were fed 227 g of grain, with the additives, and ad libitum hay for 23 d. On d 20, ewes were IV-injected with dexamethasone (DEX) at a rate of 0.4 mg/kg BW/day for 3 d. D 0, 20 and 23 blood draws were used to quantify whole blood gene expression of IL-8-Rβ and L-selectin (qPCR), isolated-neutrophil L-selectin protein abundance (Western blot) and neutrophil functional activity (phagocytosis and oxidative burst capacity, flow cytometry). Data were analyzed with 2 contrasts: Control vs. OmniGen (OGAF + OGPRO) and OGAF vs. OGPRO, and significance declared at P ≤ 0.05. Feed intake and BW gain did not differ (P > 0.05) between treatment groups during the study. L-selectin gene expression was greater for OmniGen-fed ewes at d 20 (P = 0.05) and 23 (P < 0.01). Pre-DEX challenge, IL-8-Rβ gene expression, L-selectin protein abundance, and neutrophil functional activity did not differ (P > 0.05) between treatment groups. Following the DEX challenge, OmniGen increased IL-8-Rβ gene expression (P = 0.02), L-selectin protein abundance (P = 0.03), neutrophil phagocytosis (P < 0.01) and oxidative burst activity (P < 0.01). No differences were observed (P > 0.05) between OGAF and OGPRO for L-selectin (gene expression and protein abundance), IL-8-Rβ (gene expression), nor for neutrophil functional activity before or after DEX. This study confirms OGAF and OGPRO have similar beneficial effects on preventing the immunosuppressive effects of dexamethasone.

Keywords: OmniGen, immunocompetence, immunosuppression.