Soybean Factors Relating to Gas Production by Intestinal Bacteria

SUMMARY An in vitro assay showed that toasted, dehulled, defatted soybean meal contains a gas‐producing factor and a gas‐inhibiting factor. The oligosaccharides—sucrose, raffinose and stachyose—are associated with the gas‐producing factor when incubated in thioglycollate media with anaerobic bacteria of the intestinal tract of dogs. The phenolic acids in soybeans—syringic and ferulic acid—are effective gas inhibitors in vitro and in intestinal segments of dogs. The lipids, proteins and water‐insoluble polysaccharides of soybean meal have no gas activity. During fermentation, gas production parallels the formation of monosaccharides by enzymatic hydrolysis of raffinose and stachyose. The amount and composition of gas produced from cottonseed and peanut meal were comparable to soybean meal.