The effect of food dry matter intake on the flow of amino acids at the terminal ileum for rats fed an enzyme-hydrolysed casein-based diet

The aim of the study was to determine whether food dry matter intake had an effect on endogenous ileal amino acid flows in the rat when the flows were expressed in units of mg g−1 dry matter. Eighty 200 g body weight rats were trained for 7 days to consume a casein-based diet over a daily 3 h feeding period, and then an enzyme-hydrolysed casein (MW   0.05). There were significant slopes (P < 0.05) for the other eight amino acids, although the magnitudes of the effect were small. When the data were re-examined after removing the lowest feeding level, the slopes for most of these amino acids were no longer statistically significant. The results showed that the measures of amino acid flow (mg g−1 dry matter), except for isoleucine and cystine, over a wide range of food intakes were not materially affected by food intake. From the perspective of bioassay logistics the results indicate that expressing ileal amino acid flows proportional to dry matter intake is justified over the range of intakes found in practice for determining true ileal amino acid digestibility by the enzyme-hydrolysed casein method. © 2002 Society of Chemical Industry