Effects of Humic Acids on Recovery of Salmonella Enterica Serovar Enteritidis

Abstract

Abstract Two experiments were conducted to evaluate the effects of humic acids (HA) on recovery of Salmonella Enteritidis, in an in vitro digestive system and on intestinal colonization in neonate broiler chickens. In experiment 1, two runs using an in vitro digestion model with two sources of HA (commercial or natural extraction) at 0.1 or 0.2%, and inoculated with 107 CFU/tube of S. Enteritidis, were carried out. In experiment 2, one-day-old male broiler chickens were randomly allocated to one of two groups (n=25) with or without 0.2% of isolated HA from worm compost, and challenged with 106 CFU of S. Enteritidis per chicken at 10-d old. All chicks were euthanized 24-h post challenge, and were subjected to serum fluorescein isothiocyanate dextran (FITC-d) determination. A section of ileum was removed to obtain total concentration of IgA. Ceca-cecal tonsils were removed to evaluate Salmonella recovery, total lactic acid bacteria (LAB) and total Gram negative bacteria. In experiment 1, neither concentration of commercial nor natural HA were able to reduce the recovery of S. Enteritidis in any of the simulated compartments (P>0.05). Only the crop compartment showed significant differences in pH in both trials between control and treated groups. In experiment 2, no significant differences were observed in serum concentration of FITC-d, intestinal IgA, S. Enteritidis recovery, LAB or total Gram negative bacteria in the ceca between control and treated chickens. In conclusion, no effects of HA on recovery of Salmonella Enteritidis, in an in vitro digestive system and on intestinal colonization of Salmonella, bacterial counts in ceca, intestinal IgA and serum FITC-d in neonate broiler chickens were observed. Further studies to evaluate the effect of HA under feed restriction model as an inducer of intestinal inflammation are currently being conducted.