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

Antibiotics for growth promotion in farm animal production have been used for several decades and proved to be effective in increasing animal and poultry production efficiency. However, it is widely believed that use of antibiotics as growth promoters promotes evolution and/or selection of antibiotic-resistant microorganisms in farm animals (Chattopadhyay, 2014) . Extensive researches have been done over the last couple decades to search for natural alternatives to in-feed antibiotics, and plant compounds (or phytogenic compounds) have been identified to have great potentials (Yang et al., 2015) . Among them, plant tannins have received considerable attention and probably are the most studied compounds especially for farm ruminants. Biological activities of tannins and animal responses to dietary tannins have been extensively reviewed mainly focusing on animal nutrition and production (Mueller-Harvey et al., 2006; Waghorn, 2008; Wang and McAllister, 2011; Redondo et al., 2014) . This review, after briefly summarizing some important chemical characteristics and biological properties of plant tannins, mainly focuses on the recent development in applications of anti-microbial, anti-parasitic and immunomodulation properties of tannins in farm animals.