Resistant starch is the starch that escapes degradation in the rumen. Non-resistant starch occurs when a portion of starchy feed materials is consumed by the animal. After feed intake, the feed first enters the rumen. The microorganisms in the rumen break down part of the starch. The broken-down starch is non-resistant starch. The other part escapes degradation in the rumen. This is the resistant starch. Resistant starch is broken down in the small intestine by the animal's own enzymes into glucose and thus makes a larger contribution to the glucose supply than non-resistant starch.