Porcine In Vitro Degradation and Fermentation Characteristics of Canola Co-Products without or with Fiber-Degrading Enzymes

A study was conducted to determine effects of supplementing solvent-extracted canola meal (SECM) and cold-pressed canola cake (CPCC) with fiber degrading enzymes (multi-carbohydrase); and of myrosinase in CPCC on porcine in vitro digestion and fermentation characteristics. The SECM and CPCC were obtained, and half of the CPCC was microwaved to inactivate myrosinase. Samples of SECM, CPCC and microwaved CPCC (M-CPCC) without or with multi-carbohydrase (Superzyme-CS, Canadian Bio-Systems Inc., Calgary, AB) that supplied 19,200 U of xylanase, 2,400 U of glucanase, 8,000 U of cellulase, 960 U of mannanase, 11,200 U of invertase, 80,000 U of protease, and 192,000 U of amylase/kg of feedstuff), and of M-CPCC plus myrosinase (Sigma-Aldrich Co., St. Louis, MO) that supplied 9.9 units of myrosinase/g of feedstuff) were digested using porcine pepsin and then with pancreatin. Undigested residues were subjected to porcine in vitro fermentation for 72 h. Accumulated gas production was recorded and modeled to estimate kinetics of gas production. Total VFA concentration per unit weight of residue incubated was also measured. On DM basis, CPCC and SECM contained 29.2 and 40.1% CP, respectively. Myrosinase activity for M-CPCC (7.0 U/g) was lower than that for CPCC (9.1 U/g). The IVDDM for CPCC (63.5%) was greater (P < 0.05) than that for SECM (58.4%). Myrosinase did not affect IVDDM of M-CPCC. Multi-carbohydrase increased (P < 0.05) IVDDM of M-CPCC and tended to increase (P = 0.060) IVDDM of CPCC, but did not affect IVDDM of SECM. Total gas production for CPCC was less (P < 0.05) than that for SECM (89.6 vs. 105.9 mL/g DM, respectively). Multi-carbohydrase reduced (P < 0.05) total gas production for CPCC and SECM. Total VFA production for CPCC was lower (P < 0.05) than that for SECM (1.99 vs. 4.29 mmol/g DM, respectively). Also, total VFA production for CPCC was lower (P < 0.05) than that for SECM (0.73 vs. 1.79 mmol/g DM, respectively). Myrosinase had no effect on total gas or VFA production. Also, multi-carbohydrase did not affect total VFA production of the canola co-products. In conclusion, CPCC was more digestible than SECM, whereas undigested residues of SECM were more fermentable than that of CPCC. Multi-carbohydrase had limited effect on IVDDM of SECM, but increased IVDDM and reduced fermentation of CPCC or M-CPCC, implying that multi-carbohydrase shifted digestibility of CPCC and M-CPCC from fermentation towards digestion. Myrosinase had limited effect on IVDDM and fermentability of CPCC and SECM.