Review article The equine gastro-intestinal tract: An overview of the microbiota, disease and treatment L.M.T. Dicks n , M. Botha, E. Dicks, M. Botes Department of Microbiology, University of Stellenbosch, Stellenbosch 7600, South Africa article info Article history: Received 5 April 2013 Received in revised form 7 November 2013 Accepted 27 November 2013 Keywords: Equine GIT Microbiota Lactic acid bacteria Probiotics abstract Horse is a hindgut fermenter, i.e. most microbial activities take place in the large intestine which constitutes approximately 60 per cent of the gastro-intestinal tract (GIT). The feed reaches the large intestine after approximately 3 h and is fermented for 36–48 h in the caecum. This rate of transition is only possible if the roughage component of the feed is kept optimal. A diet rich in starch leads to an imbalance in gastro-intestinal microbiota, which may lead to colic and often death. Lactic acid bacteria form a major constituent of the microbiota in the GIT, especially in the large intestine, and produce most of the volatile fatty acids (VFA) needed for energy. Production of antimicrobial compounds, including antimicrobial peptides (bacteriocins) may prevent the growth of pathogens and keep a healthy microbial balance in the GIT. Lactic acid bacteria may also play a role in stimulation of the immune system. & 2013 Elsevier B.V. All rights reserved. Contents 1. Introduction ............................................................................................ 69 2. Microbiota in the gastro-intestinal tract...................................................................... 71 3. Molecular techniques used to determine microbial diversity ..................................................... 72 4. Digestion .............................................................................................. 72 5. Gastro-intestinal related disorders associated with microorganisms ............................................... 74 6. Antimicrobials .......................................................................................... 75 7. Probiotics .............................................................................................. 76 8. Gene transfer amongst gastro-intestinal bacteria .............................................................. 77 9. Conclusion ............................................................................................. 78 Conflict of interest statement .............................................................................. 78 References ............................................................................................. 78 1. Introduction Horse (Equus caballus) is a monogastric, hindgut ferment- ing animal, i.e. most of the feed is degraded in the caecum and colon (Fig. 1). Production of large quantities of saliva (10–12 L/day) helps to transport the feed through a 1.2–1.5 m long oesophagus and buffers the digesta (Cunha, 1991). The oesophagus enters the stomach at the oesophageal section Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/livsci Livestock Science 1871-1413/$ - see front matter & 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.livsci.2013.11.025 n Correspondence to: Department of Microbiology, University of Stellenbosch, Private Bag X1, Matieland, 7602 Stellenbosch, South Africa. Tel.: þ27 21 8085849. E-mail address: lmtd@sun.ac.za (L.M.T. Dicks). Livestock Science 160 (2014) 69–81