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Abstract
The presence of Salmonella in poultry continues to be a problem in the industry. We evaluated the effect of 2-nitro-1-propanol (NP) on the recovery of Salmonella from the internal organs of layers and broilers as well as on the ileum immune response to Salmonella infections. In the first experiment, laying hens were orally challenged with a nalidixic acid resistant Salmonella Enteritidis (SENR) and supplemented with different levels of NP. Although there were numerical decreases in the number and prevalence of SENR in the L/GB, spleen, ovary, ceca and fecal samples, the difference among the treatments was not statistically significant. NP supplementation at both levels downregulated (P < 0.05) the mRNA expressions of TLR-4 and IL-6 in the ileum of the hens. In the second experiment, broilers were challenged with a nalidixic acid resistant Salmonella Typhimurium (STNAR) and supplemented with different levels of NP. Bird performance was not significantly different among the treatments at any point during the 21-day trial. Supplementation with 200 ppm NP resulted in a decline (P < 0.05) in fecal shedding at 6 dpi. No significant difference in STNAR prevalence was detected in the L/GB and spleen samples, but 200 ppm NP supplementation showed a (P < 0.05) reduction in STNAR numbers in ceca collected on day 11. Although the mRNA expressions of TLR-4, IL-1 and IL-10 were detected in all treatment groups at the end of the study, there was no statistically significant difference in the expression of these genes by 100 ppm of NP supplementation. However, the mRNA expression of IL-6 was upregulated (P < 0.05) by 200 NP of supplementation compared to positive control. Overall, NP showed a bactericidal effect against Salmonella by decreasing (P < 0.05) STNAR presence in the ceca and feces of broilers, and it downregulated (P < 0.05) the mRNA expressions of TLR-4, IL-6, INF- and IL-10 playing vital roles in the ileum immune response to SENR infection in hens. However, the mechanism of actions and effective dose needs to be determined by further research in order to provide the industry with another method to inhibit Salmonella infections in poultry.