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Nutrient Digestibility of Solvent-extracted B. napus and B. juncea Canola Meals and Their Air-classified Fractions Fed to Ileal-cannulated Grower Pigs
Energy and nutrient digestibility of solvent-extracted canola meal (CM) is limited in pigs by its relatively high fiber content. The fiber-rich seed hull is denser than the oil-free cotyledons. By utilizing streams of air, air-classification partially separates these seed components based on their different density and size to produce a low-fiber, light-particle fraction and a high-fiber, heavy-particle fraction. Compared with parent CM, ADF and NDF were reduced by 31.9 and 29.5% in the light-particle fraction and enriched by 16.5 and 9.0% in the heavy-particle fraction, respectively (DM basis). Mean particle size of parent CM, light- and heavy-particle fraction was 638, 18.9 and 76.1µm, respectively. To determine the nutrient digestibility of CM and their air-classified fractions, Brassica (B.) napus and B. juncea CM and their 2 air-classified fractions were evaluated in a 2 × 3 factorial arrangement together with a basal diet and an N-free diet. The experiment was conducted as an 8 × 8 Latin square feeding diets containing 40% B. napus or B. juncea CM or their air-classified fractions and 60% basal diet. The N-free diet served to subtract basal endogenous AA losses. Eight ileal-cannulated barrows (32 kg) were fed the 8 diets at 2.7 × maintenance DE for eight 11-d periods. Feces and ileal digesta were collected sequentially for 2 d each at the end of each period. The apparent total tract digestibility (ATTD) of GE and predicted NE value was 7.8 and 10.0% greater (P < 0.001) for B. juncea than B. napus CM (8.0 MJ/kg NE); and 5.3 and 10.8% greater (P < 0.001) for the light-particle fraction than parent CM (8.3 MJ/kg NE); and 3.8 and 7.2% lower (P < 0.001) for the heavy-particle fraction than parent CM, respectively. The standardized ileal digestibility (SID) of His, Ile, Val, Asp, and Tyr were greater (P < 0.05) for B. juncea than B. napus CM. The SID of Trp, Glu, Pro, and Tyr were greater (P < 0.05) in light-particle fraction than parent CM. The SID of Arg and Lys was lower (P < 0.05) in heavy-particle fraction than parent CM. In conclusion, B. juncea CM had greater dietary energy and AA digestibility than B. napus CM due to the reduced fiber content. Air-classification of CM increased its dietary energy and AA digestibility in pigs due to reduced fiber content and decreased particle size.
Keywords:
air classification, canola meal, digestibility, pig