Digestibility and intestinal fermentability of canola meal from Brassica juncea and Brassica napus fed to ileal-cannulated grower pigs

Abstract

Yellow-seeded Brassica (B.) juncea is a novel canola species. Therefore, its meal co-product requires feed quality evaluation and comparison to conventional, dark-seeded B. napus canola meal for pigs. The B. juncea canola meal contains less fibre than B. napus canola meal (190 vs. 260g NDF/kg, as is), but also less lysine (20.3 vs. 22.1g/kg). Nutrient digestibility and fermentibility of B. juncea and B. napus canola meal were assessed in a 2×2factorial arrangement. Six ileal-cannulated pigs (47kg BW) were fed six diets in a 6×6 Latin square: basal diet (460g wheat/kg and corn starch), 4 diets with 460g wheat/kg and either B. juncea or B. napus canola meal at 250 or 500g/kg replacing corn starch, sugar and canola oil, and an N-free diet based on corn starch. The B. juncea canola meal had greater (P<0.05) CATTD of gross energy than B. napus canola meal (0.70 vs. 0.63) most likely due to its lower fibre content. Ileal total VFA concentration was lower (P<0.001) in pigs fed B. juncea than B. napus canola meal diets (15.2 vs. 20.8μmol/g of wet digesta). In pigs fed B. juncea canola meal instead of B. napus canola meal diets, the molar ratio was greater (P<0.01) for digesta propionate and faecal acetate, but lower (P<0.05) for digesta and faecal butyrate. Canola meal species did not affect the CAID of gross energy, CSID of amino acid and faecal VFA content. The digestible energy (DE) value was greater (P<0.01; 12.1 vs. 10.9MJ/kg, standardised to 100g/kg moisture) for B. juncea than B. napus canola meal. Increasing dietary inclusion of canola meal up to 500g/kg reduced (P<0.01) diet digestibility of gross energy but not amino acids and decreased (P<0.05) intestinal fermentability of B. napus but not B. juncea. In conclusion, B. juncea canola meal had greater fermentability and ATTD of gross energy than B. napus canola meal, but digestibility of amino acids did not differ. Increasing dietary inclusion of canola meal up to 500g/kg reduced digestibility of gross energy but not digestibility of AA. Fermentability of B. napus canola meal but not B. juncea canola meal decreased in the pig intestine with increased dietary inclusion. Hence, yellow-seeded B. juncea canola meal had a greater DE value, similar amino acid digestibility as conventional dark-seed B. napus canola meal and may limit protein fermentation in the pig intestine.