A variety of factors influence the results of digestion studies design
ed to measure ruminal disappearance of nutrients and flow of nutrients
to the intestine. Feed intake, marker usage, sample collection, stati
stical design, and computation methods are among the factors discussed
in this review. Guidelines are provided for presentation and interpre
tation of data from digesta flow studies. The scientific value of such
studies often is limited because 1) replication, relative to expected
variation, is inadequate and 2) experimental animals are not maintain
ed under conditions similar to those used in normal production. Becaus
e studies conducted with inappropriate methods or inadequate replicati
on are of little value and waste resources, validation of techniques i
s critical, and individual researchers should strive to verify their t
echniques.