Immune Response and Salmonella Clearance in Broiler Chickens after Fed Arginine, Vitamin E and Prebiotics
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Four experiments were conducted to evaluate effects of arginine (ARG), vitamin E (VE) and mannanoligosaccharide (MOS) on immune response and clearance of Salmonella in broiler chickens. There were 4 groups in Exp.1 (E.1) and E.2: antibiotic-free diet (CTL-); diet with antibiotic (CTL+); ARG and VE (AVE); ARG, VE and MOS (AVM). Birds were infected with 10^6 CFU/ml of a novobiocin and nalidixic acid resistant Salmonella enteric Serovar Typhimurium (ST) at d 7 (E.1) or at d 3 (E.2). In E.3 and E.4, there were three groups: CTL, AVE and AVM; at d 3, birds in E.3 were infected with 10^2 CFU/ml ST and birds in E.4 were infected with 10^6 CFU/ml ST. The following were analyzed for four experiments: Oxidative burst heterophils response (OBHR) and monocytes response (OBMR); Lymphocyte proliferative response (LP); antibodies concentrations in serum; chicken body weight (BW), cecal Salmonella concentration; gut parameters. In E.1, both AVM and AVE diet decreased OBHR; birds fed AVM showed the highest IgA level, birds fed AVM had higher IgM than CTL+ and had the lowest Salmonella population. Birds fed AVE showed higher LP than CTL- in E.1 and E.2. From E.1 and E.2, AVM decreased chicken innate immune response at a younger age and improved adaptive immune response when birds were older than 16 d. AVM reduced ST when administrated later (d 7) versus early (d 3). In E.3, no BW and Salmonella counts differences were found; birds fed AVM had a higher IgA than AVE but similar to CTL at d 17. Chickens fed CTL had the highest OBHR at d 17, chickens fed AVM had the highest LPR at d 17. In E.4, chickens fed AVM showed higher BW than CTL at d 17 and d 24. Also no Salmonella counts differences were found. Chickens fed AVE had higher LPR than chickens fed AVM at d 17. These results are consistent with results from E.1 and E.2. Overall, diet AVM has different effects on chicken immune response when chicks were infected at different age; higher level of ARG and VE improved immune response and improve gut health.