Fermentation of stachyose and raffinose by hind-gut bacteria of the weanling pig

Two pigs were weaned at 28 d of age, and one pig each was placed on a corn-soy (CS) or a corn-soy diet containing 40% lactose (CSL). After 28 d a fecal sample was taken from each pig. The fecal bacterial community was fractionated and used as a source of inoculum to determine if high levels of lactose added to CS diets would modify the structure of the hind-gut microbial community and the in vitro breakdown of stachyose (soy molasses served at the source of stachyose) and raffinose. Bacterial growth rate tended to the higher with the CSL diet. Higher growth rates for bacteria from the CSL-fed pig were supported by the higher acetate: propionate production when compared to the CS diet. All the stachyose and raffinose disappeared during the 48 h fermentation. To our knowledge, this is the first report that stachyose or raffinose are completely fermented by the hind-gut bacteria of the weanling pig, and that this process can be affected by the addition of high levels of lactose to the diet.