Physiology/Pathology/SCAD I

S OF PAPERS 195 M8 Pretreating primary macrophages (Mɸ) with Bacillus subtillus but not mannan oligosaccharide increases nitric oxide production after Salmonella enteritidis challenge. Marta Viguie*UG, Kimberly Livingston California Polytechnic State University, San Luis Obispo, CA Direct-fed microbials (DFM) including probiotic and prebiotic additives have been shown to improve growth and feed conversion when incorporated into animal diets. Additionally improvements in the ability of the animal to withstand challenges from bacteria have been observed. However, the mechanisms by which the additives improve immunological response have not been fully elucidated. The objective of this experiment was to better understand how DFMs may alter macrophages (Mɸ) ability to clear a Salmonella enteritidis (SE) challenge. Primary Mɸ were isolated from chickens and pretreated for 24 h with Bascillus subtilus (BS; 4500 CFU/ml), and/or mannan oligosaccharide (MOS; 0.075 ug/ ml), extracted from the cell wall of Saccharomyces cerevisiae. Mɸ were then challenged with SE for 1 h. Nitric oxide(NO) in the supernatants was evaluated. In addition culture lysates were evaluated to determine Mɸ killing ability of SE. Pre-treatment of Mɸ with BS or MOS did not improve SE killing as determined by plating the lysates and counting CFU. However, Mɸ pretreated with BS did have greater NO production than Mɸ pretreated with MOS or left alone (P<0.001). In conclusion, BS does appear to have a direct effect on Mɸ when co-cultured in-vitro, which leads to increased NO production when challenged with SE.