Assessment of the phosphorus digestibility of 4 high endogenous phytase diets and of 14 feedstuffs used in growing pigs

To evaluate the phosphorus digestibility of 14 feedstufs and 4 high endogenous phytase diets, balance trials were performed in growing pigs weighing near 40 kg. These diets were formulated to provide between 200 and 1000 phytase units/kg diet by using the feedstuffs screened in the digestibility trial. Phosphorus digestibility of the feedstuffs ranged from 12.4, rice bran to 49.5 %, wheat bran and wheat middlings. The phosphorus digestibility of the diets increased as the dietary phytase increased (by 28 % corresponding to +500 U/kg). Phytase activity was a good predictor of the phosphorus digestibility of diets given in the form of mash (equation between both parameters was calculated).Unlike phytase activity, the digestible phosphorus content of the feedstuffs did not seem to be an additive criterion.