A thymol-based blend of botanicals reduces Salmonella induced inflammation by altering key inflammatory signaling intermediates differentially depending on dose and in a manner distinct from in-feed antibiotics

Inducing inflammation in response to pathogen infection is known to be an energy-intensive process. An extended state of inflammation in production animals can be detrimental to performance parameters. Here, we compare two doses of a microencapsulated thymol-based feed additive blend and two different antibiotics in the context of a Salmonella Enterica subsp. Enterica serovar Enteritidis (SE) challenge. A total of 500, day-old, straight run chicks (Ross 708) were placed in floor pens (50 chicks/pen) and assigned to 5 groups with 2 replicates each. The groups were all fed with basal diets, without supplementation (Control) or supplemented with: tylosin at 25 g/MT (Tylosin); neomycin sulfate at 100 g/MT (Neomycin); or a microencapsulated thymol-based blend of botanicals at inclusions of 500 g/MT (Blend 500) or 1000 g/MT (Blend 1000). All the pens were orally challenged at day 4 with SE at 10⁵ CFU/bird. At 7, 14, 21, and 35-days post hatch, ten animals from each pen were weighed and euthanized in order to culture enumerate SE in the ceca and determine SE prevalence in the liver. Gene based prevalence, gene expression, and kinome analysis were performed on jejunum samples collected at day 35. The higher dose of the tested botanical, Blend 1000, showed a statistically significant increase in final body weight relative to the other groups, indicating an energy benefit for this group. The Blend 1000 also showed a reduction in protein phosphorylation that corresponds to reduced inflammatory status that was unique compared to Blend 500 and the antibiotics. These birds also showed a clearance of orally inoculated SE demonstrating that reduced inflammation can benefit the broiler chicken in clearance of bacteria while maintaining growth.