As the demand for alternatives to antibiotic growth promoters (AGPs) increases in food animal production, phytobiotic compounds gain in popularity due to their ability to mimic the desirable bioactive properties of AGPs. Chestnut tannins (ChT) are one of many phytobiotic compounds utilized as feed additives, particularly in South America, for broiler chickens due to its favorable antimicrobial and growth promotion capabilities. While studies have observed the microbiological and immunological effects of ChT, there is a lack of studies evaluating the metabolic function of ChT in the host. Therefore, the objective of this study was to characterize the cecal metabolic changes induced by ChT inclusion and how they relate to growth promotion.
A total of 500 day-of-hatch Cobb 500 chicks were separated into five feed treatment groups: control, 1% ChT, 0.2% ChT, 0.08% ChT, and 0.03% ChT. The cecas from all the chicks in the treatment groups were collected on days 2, 4, 6, 8, and 10 post-hatch. The cytokine mRNA qRT-PCR was determined using TaqMan gene expression assays for IL-1B, IL-6, IL-8, IL-10, and IFN-γ quantification. The cytokine expression showed highly significant increased expressions of IL-6 and IL-10 on days 2 and 6, while the other pro-inflammatory cytokines did not have significantly increased expression. The results from the kinome array demonstrated that the cecas from birds fed with 1% ChT had significant (p < 0.05) metabolic alterations based on the number of peptides when compared to the control group across all days tested.
Based on the results, the increased expression of IL-6 appeared to be strongly indicative of altered metabolism while the increased expression of IL-10 indicated the regulatory effect against other pro-inflammatory cytokines other than IL-6. The ChTs initiate a metabolic mechanism during the first ten days in the broiler. For the first time, we show that a phytobiotic product initially modulates metabolism rather than immunity while also potentially supporting growth and feed efficiency downstream. In conclusion, an IL6-mediated immunometabolic phenotypic alteration in the ceca of chickens fed ChT may indicate the importance in the gut of enhanced broiler health.