This research was conducted to study the kinetic of phosphorus (P) in tissue of swine growing phase fed diets containing crescent levels of total phosphorus (.30, .40, .51, .65 e .73%), using 32P as tracer. The rate of 32P retention and the relative specific activity and standard in the bone, liver, heart, kidney and muscle were the markers of inorganic P concentration. Ten commercial crossbred barrows, with 20 kg, were allotted to a completely randomized design in a split plot arrangement. The pigs were kept in metabolic cage for a seven-day period of adaptation and seven-day for blood samples collection. In the first day of the collection period, each animal was injected intravenously with 7.4 MBq of 32P, as metabolic tracer. On 8th day the animals were slaughtered and sample of tissues were collected. The mean values of the P concentration, of 32P retention and of the relative specific activity in bone, liver, heart, kidney and muscle were 65.79, 10.34, 8.39, 10.99, and 6.64 mg/g DM; .0125, .0156, .0176, .0178, and .0165% and .6292, .6286, .5718, .5215, and .6506, respectively. The levels of P intake did not affect the concentration of P in bones, liver heart, kidney and muscle. The 32P retention in the tissues decreased in the following order: kidney, heart, muscles, liver and bone, independently of the amount of P intake. The P exchanges between the plasma and the tissues, bone, liver and kidney, increased with the increasing of the P intake from the diet.
kinetic; radiophosphorus; swine; isotopic dilution; 32P
