The objective of this experiment was to determine the appropriate level of phytase (0,300, 600 and 900PU/kg of the diet) to be added in swine diets containing two levels of crude protein (CP), one in the demand of the animal (18% - NRC, 1988) and another in lower level (16%), on the quality of the carcass and the bony parameters of the pigs. Twenty four pigs with an initial average weight of 18.4kg and slaughtered at the end of the experiment (after 28 days) with an average weight of 32.3kg were used. The amount of total ingested nitrogen and the average live weight of the pigs were evaluated before slaughter. After slaughter, the amount of nitrogen in the pig carcass and concentration of the nitrogen in the intestinal content were analised. The bony parameters evaluated were: concentration of ashes, phosphorus and calcium in the coccigea vertebra and in the metacarpe. It was observed that pigs that consumed the diets with phytase were slaughtered with larger weight (P<0.092); however, the enzyme did not show effect of the carcass parameters (P>0.20). A better nitrogen use (P<0.109) and bony composition (P<0.05) of the animals fed with diets containing 16% of CP plus enzyme levels among 297 - 560PU/kg were found. These effects were absent in pigs who consumed diets with 18% of CP plus phytase.
calcium; carcass; enzyme; nitrogen; phosphorus; phytate
