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

Purple prairie clover has been demonstrated as a potential forage for mitigation of E. coli O157:H7, a deadly food-born pathogenic bacteria that reside in ruminant digestive tract Huang et al., 2015) . Huang et al. (2015) found that lambs challenged with E. coli O157:H7 fed diets containing 36 g of purple prairie clover CT/kg DM shed significant less E. coli O157:H7 than lambs fed diets without CT. The same CT were also demonstrated to decrease E. coli fecal shedding in cattle grazing native pasture containing 16 to 20 g CT/kg DM . In addition, adding chestnut tannin at the concentration of 15 g/kg DM decreased fecal shedding of E. coli for cattle fed hay diets (Min et al., 2007) . However, other tannins such as that from sainfoin and S. lespedeza at lower concentration (<13.5 g CT/kg DM) had no effect on fecal E. coli shedding (Lee et al., 2009a,b; Berard et al., 2009 ). Supplementation of A. nodosum meal at the dietary concentrations of 10 to 20 g/kg DM significantly decreased E. coli O157:H7 fecal shedding in cattle (Table 1) . Tannin concentration was not reported in these studies, but A. nodosum is brown algae contain high levels of PT . These researches demonstrated that feeding plant tannins could be a practical method to effectively decrease the presence of E. coli O157:H7 in ruminant digestive tract thereby reduce the risk of carcass contamination and hence enhance the food safety.