Nutritional evaluation and processing of canola hulls for ruminants

This study examined the nutritional value of canola hulls for ruminants and the effects of processing on in situ ruminal nutrient disappearance. VI and apparent DMD, CPD, ADFD and NDFD (%) and DE content (MJ kg−1 DM) of canola hull supplemented diets were determined in a total tract digestibility trial using 12 ram lambs. The dietary treatments were 100% alfalfa hay; 75% alfalfa hay: 25% canola hulls; 50% alfalfa hay: 50% canola hulls; 25% alfalfa hay: 75% canola hulls. In situ disappearance of treated and untreated canola hulls was determined using two fistulated cows. Processing treatments included: untreated hulls; ammoniation; solvent extraction; and ammoniation and solvent extraction. As canola hull inclusion rate increased, DM intake, DMD, CPD, ADFD and NDFD decreased (P < 0.05) linearly. Digestible energy values did not differ between diets, suggesting that canola hulls have a DE value (9.3 MJ DE kg−1 DM) similar to the alfalfa hay used in the trial. Ruminal nutrient disappearance and kinetic parameters were not improved by ammoniation or solvent extraction. It is concluded that supplementation of canola hulls to alfalfa based diets will reduce nutrient digestibility and DM intake when fed to growing ram lambs. Ammoniation is not an effective treatment for improving in situ nutrient disappearance from canola hulls.