Effect of Tail-End Dehulling of Canola Meal on Apparent and Standardized Total Tract Digestibility of Phosphorus When Fed to Growing Pigs

Tail-end dehulling of canola meal (CM) has been identified as a means to reduce dietary fiber and increase crude protein content in the dehulled meal. This procedure also increases the total and non-phytate phosphorus (P) content in the dehulled meal. However, it is unclear if dehulling affects P digestibility in the different fractions (i.e. the dehulled meal and the coarse fraction) and if it differs when fed to growing pigs at 2 different body weights (BW). Therefore, 2 experiments were conducted to determine the effect of tail-end dehulling of CM on apparent (ATTD) and standardized (STTD) total tract digestibility of P in growing pigs. Diets containing non-dehulled (RCM), dehulled (DCM) and coarse (CCM) solvent extracted CM from Brassica napus black as the only source of P were fed to growing pigs at 2 different BW. A total of 48 pigs were used for the two experiments. In Exp. 1, 24 barrows [(Yorkshire-Landrace) x Duroc] of 24.5 + 1.68 kg BW were individually housed in metabolism crates and fed the experimental diets for 10 d for total fecal collection. In Exp. 2, 24 barrows with an average initial BW of 73.8 + 4.93 kg were used; experimental diets and fecal collection procedures were the same as Exp. 1. Each experiment used 6 replicate pens per treatment. A P free diet was used to determine basal endogenous losses of P. Data were analyzed as a completely randomized design using the MIXED procedure of SAS. In Exp. 1, the ATTD and STTD of P were greater (P < 0.05) for DCM (42.4 and 46.1%) than for the RCM (32.0 and 35.7%) and CCM (24.5 and 28.4%) diets. In Exp. 2, the same trend continued, the ATTD and STTD of P were greater (P < 0.05) for DCM (38.7 and 42.8%) than for the CCM diet (22.6 and 26.8%), whereas the values for RCM diet were intermediate (31.0 and 35.0%) and not statistically different from the DCM and CCM. In conclusion, dehulling canola meal increased apparent and standardized total tract digestibility of P in growing pigs of different BW.