Abstract
The co-product canola meal contains little fat and has been used in swine production as a protein source for several decades. More recently, locally produced canola cake has also become available that contains important quantities of residual oil. Both canola co-products contain a considerable quantity of phosphorus (P) with low availability. Phytase supplementation can increase P digestibility in canola meal but its efficacy remains unclear for canola cake containing high residual oil. To explore whether phytase supplementation can increase digestibility of P and other nutrients in canola cake, four diets containing 500 g of locally produced cold-pressed canola cake or canola meal, with or without supplemental phytase (Ronozyme HiPhos; Aspergillus oryzae origin)/kg, were fed to seven pigs (initial body weight; 55.9 ± 3.8 kg) in four 9-day periods following a 4 × 4 Latin square plus a 4 × 3 Youden square. Phytase supplementation increased phytase activity from below the detection limit to reach a minimum of 1000 phytase units/kg in the canola meal and cake diets; respectively. Phytase supplementation increased (p < 0.05) coefficients of ileal and total tract digestibility of P by 60% and 46% for canola meal and 76% and 57% for canola cake, respectively, but did not affect the digestibility of crude protein or gross energy. Ileal or total tract digestibility of P did not differ between the canola cake and canola meal diets in growing-finishing pigs. In conclusion, fungal phytase is effective in increasing the P digestibility of canola cake similar to in canola meal fed to growing-finishing pigs. The similar ileal or total tract digestibility of P in canola meal and cake diets either with or without phytase supplementation indicated that the residual oil in canola cake did not affect P digestion and did not affect the efficacy of phytase in increasing P digestibility.