Reduction of cecal colonization and fecal shedding of Salmonella Typhimurium in broilers fed proprietary zinc- or manganese-amino acid complexes

Abstract

SUMMARY: Intestinal Salmonella colonization of chickens represents one of the most important food safety hazards. Mitigating this problem is challenging since Salmonella is a commensal in poultry. In this study, we assessed the ability of proprietary zinc-amino acid and manganese-amino acid complexes to reduce Salmonella colonization and shedding in commercial broilers receiving such trace minerals in the finisher diet. Broilers were orally challenged with Salmonella Typhimurium on 5 occasions between d 1 and d 20 of age. After confirming that the chicks were shedding Salmonella in the feces on d 22, broiler chicks were fed a standard diet containing: proprietary zinc-amino acid complexes; proprietary zinc- plus manganese-amino acids complexes; ZnSO4 + MnSO4; ZnSO4; or no additional supplements. Fecal samples were obtained on 4 occasions and were subjected to enumeration of Salmonella. Birds were euthanized on d 42 and ceca were removed for enumeration of Salmonella. Salmonella fecal shedding and cecal colonization were significantly decreased in broilers fed Zn-amino acid complexes, when compared to broilers fed Control diets. Feed efficiency and body weight gain were greater in broilers fed proprietary Zn-amino acid complexes or proprietary Zn- plus Mn-amino acids complexes compared to birds fed the Control or ZnSO4 + MnSO4 diets. Furthermore, real-time quantitative RT-PCR-based studies revealed enhanced expression of various cytokines, chemokines, tight junction proteins, and beta-defensins in birds fed the higher dose of the Zn-amino acid complexes. Thus, it appears that the Zn- and Mn-amino acid complexes reduce Salmonella carriage and improve feed efficiency possibly by optimizing the innate immune response to Salmonella and by improving gastrointestinal epithelial barrier.

Keywords

• Salmonella
• zinc
• manganese
• broiler chicken