Potential and challenges of tannins as an alternative to in-feed antibiotics for farm animal production

Huang, Qianqian; Liu, Xiuli; Zhao, Guoqi; Hu, Tianming; Wang, Yuxi

Tannic acid is a HT from varying plants including tara pods (Caesalpinia spinosa), gallnuts from Rhus semialata, Quercus infectoria or Sicilian Sumac leaves (Rhus coriaria). Lee et al. (2010) reported that addition of tannic acid at the dietary levels of 0.0125% to 0.1% negatively impacted growth performance, hematological indices and plasma iron status of pigs, and linearly reduced faecal coliform bacteria count. However, the same authors found that feeding 0.0125% of tannic acid had no effect on growth performance, but negatively affected blood hematology and plasma Fe status when pigs were fed Fe deficient diets. It was also observed Lee et al. (2009a,b) (continued on next page) that total anaerobic bacteria, Clostridium spp. and coliforms were decreased but Bifidobacterium spp. and Lactobacillus spp. were increased by 0.0125% tannin acid (Lee et al., 2009a,b) . Tannic acid at the concentration of 0.5% increased growth performance and fat content in breast and thigh meat, but reduced blood glucose concentration and cholesterol content in the liver of broiler chicken (Star cevi c et al., 2015) . It is also reported that tannic acid at the dietary concentrations of 0.75% and 1.5% did not alter Salmonella cecal culture-positive chicks or the numbers of Salmonella typhimurium in the cecal contents of broiler chickens (Kubena et al., 2001) . Increasing concentrations to 2.5% and 3.0% reduced weight gain and protein efficiency and impaired the immune function of growing chickens by decreasing weight of bursa of fabricius, thymus and spleen, reducing total immunoglobulin (Ig) M and IgG immunoglobulin levels and total white blood cells and absolute lymphocytes in a dose-dependent manner (Marzo et al., 1990) . Ebrahim et al. (2015) found that 1% of tannic acid decreased body weight gain and feed intake but improved the fatty acid profile of breast muscle of broilers under heat stress by decreasing monounsaturated fatty acids. From above results, it seems that application rates of tannic acid in both swine and poultry are higher than those of other sources of tannins, but No effects on feed intake, improved feed efficiency; no effect on gastric mucosa Cappai et al. (2013) rarely result in positive effect on animal performance although increased antioxidant status were reported in several studies. High concentrations (e.g., 1%) appear to be toxic to animals in terms of decreasing production efficiency.