Pettigrew’s laboratory at the University of Illinois has begun studies examining the effects of dietary fibre on resistance to enteric disease in pigs. Comparing the use of several cereals varying in fibre content, the researchers were able to carefully draw a few conclusions about the fibre’s effects.

With the growing ethanol industry, huge amounts of DDGS have the potential to be incorporated into livestock rations and may carry the potential to control some diseases in livestock, said Mr Pettigrew.

“In very general terms, fibre can be divided into soluble and insoluble non-starch polysaccharides (NSP). The microbes that inhabit the lower gut can ferment most soluble NSP rapidly, but ferment insoluble NSP slowly, if at all. DDGS contain a relatively high level of fibre and the NSP are mostly insoluble," he said.

He outlined three concepts of the relationship of dietary fibre to enteric disease that have been proposed. They include:

• Fermentable (soluble) fibre is beneficial because it supports the proliferation of commensal (normal) bacteria and these bacteria inhibit the growth of pathogens
  
• Fermentable fibre is detrimental because it serves as a substrate for pathogens
  
• Non-fermentable (insoluble) fibre is beneficial because of a variety of physiological effects.

“The lack of clarity on this issue is frustrating and expensive because the relationship of dietary fiber to enteric disease is potentially valuable in maintenance of animal health,” said Mr Pettigrew.
While a series of experiments have failed to show such protection clearly, the notion persists, and perhaps because of perceived benefits on farms, he added.

“It appears likely that any protective effect of DDGS derives from its high fibre content, although effects of residual yeast from the fermentation cannot be discounted. But it's too early in the study to come up with finite conclusions and recommendations,” he expained.