Alternative techniques for measuring nutrient digestion in ruminants.

Because in vivo measurement of nutrient digestion in the rumen and small intestine requires ruminally and intestinally cannulated animals that are expensive, labor-intensive, and subject to error associated with markers and inherent animal variation, alternative techniques have been developed. Researchers have proposed various in situ or in vitro procedures for estimating ruminal and small intestinal nutrient digestion. This review summarizes these alternative techniques.