The objective of this work was to evaluate the in situ disappearance of canola meal treated with water (control), in autoclave at 127ºC for 30 min (CC), with 15% of Acacia mearnsii tannin (CT) and tannin followed by autoclaving (CTC). The effect of these treatments on in situ disappearance of dry matter (DM) and crude protein (CP) was evaluated by the nylon bag technique, using two rumen fistulated Holstein cows. The estimates of effective degradation of DM for control, CC, CT and CTC were 74.5, 64.2, 75.1, and 70.5%, and effective degradation of CP were 86.5, 64.0, 82.6, and 69.9%, respectively, assuming rumen of 5%/h outflow rate. No effect of tannin treatment on DM degradation was reported, however, there was a small influence on CP degradation. The treatments (CC and CTC) reduced DM and CP degradation. The heating effect, after tannin treatment, was smaller than its isolated effect, resulting in significant interaction. The heat treatment was the most effective to reduce ruminal degradation of canola meal DM and CP.
degradability; canola meal; protected protein; tannin
