Effects of Different Commercial Formulations of Tannic Acid Added at an Equal Inclusion Rate on Intestinal Health and Microbial Flora in Yellow-Feathered Broilers

Antibiotic restrictions require safe alternatives. Tannic acid has antimicrobial and gut-regulatory properties, but data on its formulations are limited. This study employed an equal raw material inclusion design, adding three commercial tannic acid products at 250 mg/kg to compare their effects in yellow-feathered broilers. A total of 432 broilers were assigned to four groups: control, coated (LCTA), powdered (LPTA), or granular (LGTA) tannic acid. Growth performance did not differ among groups. LPTA numerically improved ADG and reduced serum urea, while LGTA increased triglycerides. LCTA enhanced CAT and SOD activities but also elevated MDA. All treatments reduced villus height, but LPTA improved VH/CD ratio. Claudin-1 and Occludin were downregulated; ZO-1 remained stable only in LPTA. LCTA increased IL-6; IL-10 and TNF-α decreased across treatments. LPTA appeared to maintain richness, increase diversity, and promote Bifidobacterium. The powdered form appeared to exhibit a relatively balanced profile with potential practical value, though formulation and active dose were confounded as products differed in purity (50%, 65%, 75%), resulting in different actual doses. Future studies with equalized active ingredient levels are needed to confirm formulation-specific effects.