Energy and amino acid digestibility of expeller-pressed canola meal and cold-pressed canola cake in ileal-cannulated finishing pigs

Residual oil content that increases the dietary energy value makes expeller-pressed canola meal (EPCM) and cold-pressed canola cake (CPCC) attractive feedstuffs for swine. The energy and amino acid (AA) digestibility of EPCM and CPCC were evaluated feeding six crossbred Hypor barrows (initial weight of 65.7 ± 1.7 kg) surgically fitted with a simple T-cannula at the distal ileum. Pigs were fed twice daily at 2.8 times the estimated maintenance requirement of digestible energy (DE). Diets containing 500 g/kg of either EPCM or CPCC and an N-free diet were tested in a replicated 3×3 Latin square. The oil content of EPCM was half that of CPCC (105 vs. 202 g/kg). Total glucosinolate content of EPCM was double that of CPCC (11.9 vs. 5.6 μmol/g). The apparent total tract digestibility coefficient and apparent ileal digestibility coefficient (CAID) of energy were lower (P<0.05) in EPCM than CPCC. The DE (P<0.05) and calculated net energy (NE) content were lower (P<0.001) in EPCM than CPCC (14.3 vs. 16.5 and 9.0 vs. 11.5 MJ NE/kg as fed, respectively). The CAID of lysine and cysteine was lower (P<0.05) in EPCM than CPCC. The standardized ileal digestibility coefficient (CSID) of alanine, cysteine, glycine, histidine, isoleucine, lysine and valine was lower (P<0.05) in EPCM than CPCC. However, the standardized ileal digestible content of all AA was greater (P<0.05) in EPCM than CPCC. In conclusion, lower residual oil and greater content of antinutritional factors (glucosinolates and fibre) in EPCM compared with CPCC were important factors that lowered energy digestibility and DE and NE values in EPCM compared to CPCC and likely lowered CSID of some indispensable AA in EPCM vs. CPCC, including lysine.