Influence of Moist Heat Treatment on Ruminal and Intestinal Disappearance of Amino Acids from Canola Meal

¹ Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada R3T 2N2

Three mature Angus steers fitted with large ruminal cannulas and three Holstein steers each fitted with T-shaped cannulas in the proximal duodenum and reentrant cannulas in the terminal ileum were used to study the effect of moist heat treatment on AA digestion of canola meal in each segment of the digestive tract. Canola meal was treated with moist heat at 127°C for 15 or 45 min. Degradation of AA in the rumen was estimated using small nylon bags incubated for .1, 8, 16, and 24 h in the rumen. Digestion of AA in the small and large intestines and total tract were estimated using separate sets of bags in a sequence of ruminal in situ incubation, in vitro incubation in an acid-pepsin solution, and a mobile bag technique. Heat treatment for 15 or 45 min reduced concentrations of Lys by 15.9 and 29.2% and Arg by 8.0 and 15.2%, respectively. Heat treatment for 15 or 45 min significantly reduced the degradation of AA in the rumen; the availability of AA in the small intestine increased in proportion to the decreased ruminal degradation. Digestion of AA in the large intestine was 5 percentage points higher after heat treatment for 45 min than with no heat treatment. Apparent digestion of AA in the total tract was unaffected by 15 min of heating; however, 45 min of heating reduced digestion. Moist heat treatment ranged from 75% for Lys to 154% for His with 16 h of ruminal incubation.

Key Words: canola meal • moist heat treatment • amino acid • small intestine