That substrate supply is largely a function of the diet; the supply in the lower tract is largely a function of the amount and type of indigestible but fermentable carbohydrates in the diet.

• 这些供能物质在日粮中主要是提供能量，在肠道后段则是提供一定数量和种类的不可消化但是可以发酵的碳水化合物。