The study was conducted to evaluate the biological flow of P in pigs fed diets based on corn, soybean meal, defatted rice bran (DRB) and soybean oil, with increasing phytase levels (253, 759, 1265 and 1748 PU/kg of diet), using mathematics models. The model was deterministic and compartimental, in which the gastrintestinal tract (GIT) (C1), the plasma C2, the bones (C3) and the soft tissues (liver, heart, kidney and muscle) (C4) represented the compartments. Metabolism data and kinetics of P in tissues were used in the model, obtained by the isotopic dilution technique. The parameters used were: absorption, retention, endogenous P that return to the gastrintestinal tract (GIT), dietary absorbed P, accretion, reabsorption, balance of P in bone and soft tissues and P from total absorbed that returned the GIT. The biomathematical model used is adequate to explain the P flow in growing pig. The phytase enzyme interfere in biological flow of P from compartment C1 to C3 and with the output flow of P from compartment C3 and C4 to C1. The level of 759 PU of phytase in diet of growing pig availability more efficientily the organic phosphorus for the pigs metabolism.
absorption; endogenous losses; kinetics; mathematic model; radiophosphorus
