Impact of the diet on digestive disorders of pigs, with special emphasis on proliferative enteropathy and swine dysentery

Amongst environmental factors, the composition of the diet is well understood to be a critical determinant of economic pig production, but its potential impact on specific enteric diseases is often overlooked. Pigs suffer many economically important diseases and disorders of the gastrointestinal tract (GIT), and these require control to prevent overt disease, reduce morbidity and mortality, maintain welfare, and to improve the efficiency of production. Veterinarians, feed manufacturers, nutritionists and producers have generally relied upon antimicrobial compounds such as antibiotics and dietary minerals (e.g. zinc oxide, copper sulphate) for a large part of this control. However, concern related to antimicrobial resistance and environmental contamination has resulted in questioning of these current strategies to control enteric bacterial diseases. A plethora of strategies for control have been examined and sometimes implemented, but unfortunately in practice there remains no simple and universal alternative means to reduce susceptibility to pathogens in the GIT. The current chapter focuses on sonic of the ways that the diet can influence specific enteric infections, with particular emphasis on the proliferative enteropathies (PE), caused by the intracytoplasmic bacterium Lawsonia intracclluIaris, and swine dysentery (SD), caused by the anaerobic spirochaetal bacterium Brachyspira hyodysenteriae. Both diseases remain extremely important in pigs throughout the world. A relatively small number of studies have addressed whether manipulation of diet texture and/or composition can influence the occurrence of these two diseases. Evidence to date suggests that SD may be more amenable to nutritional manipulation than PE, but irrespective of the disease, considerable variation exists in the disease severity and prevalence observed in different studies, even from the same institution. This makes it currently difficult to recommend firm dietary guidelines to prevent/reduce these two enteric bacterial diseases