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Abstract
In broiler production, there are many challenging conditions (e.g., bacterial and parasitic infection) that can be detrimental to growth performance and gut health of broilers. After the restriction of antimicrobial growth promotors, it has been essential to find appropriate AGP in broiler production. Tannic acid (TA), the standard of hydrolysable tannins, is considered as a promising AGP alternative in broiler production due to their strong antimicrobial, antioxidant, anti-inflammatory effects. However, depends on the dosages, TA can show favorable or detrimental effects in broilers because over-supplementation of TA can reduce nutrient digestibility and feed intake and compromise gut health via precipitating dietary and endogenous nutrients. Therefore, the purpose of the study was to investigate effects of supplementation of TA on growth performance, gut health, gut microbiota, bone health, body composition, and meat quantity and quality in broilers under healthy and challenging conditions. The TA showed strong antimicrobial effects against Salmonella Typhimurium and TA at sub-lethal dosages reduced swimming and swarming motility and biofilm formation against Salmonella Typhimurium in in vitro condition (P < 0.05). Approximately 10% of TA were recovered in the ceca of broilers. Supplementation of TA at levels greater than 972 mg/kg tended to reduce body weight in broilers D 21 (P = 0.05). Supplementation of TA at 1 to 2 g/kg significantly reduced S. Typhimurium load in the ceca on D 7 compared to the infected control group (P < 0.05), and average daily gain (ADG) tended to be linearly increased due to supplementation of TA in broilers infected with S. Typhimurium (P = 0.097). Supplementation of TA linearly enhanced percentage of peripheral blood CD8+ T cells on D 18 (P < 0.01). Supplementation of TA at 0.5 and 2.75 g/kg significantly reduced oocyst shedding of E. maxima compared to the E. maxima infected control group (P < 0.05), and supplementation of TA at 2.75 g/kg attenuated damaged gut permeability in broilers infected with E. maxima (P < 0.01). However, supplementation of TA upto 2 g/kg in the pelleted feed linearly reduced BW in the starter and grower phase (P < 0.05) and increased fat deposition in broilers on D 42 (P < 0.05). Therefore, whereas supplementation of TA has potential to improve growth performance and gut health in broilers under bacterial and parasitic infection condition, more studies are required to apply dietary TA in the field condition of broiler production to improve production efficiency.