Redução de fósforo em dietas para frangos com base em valores de equivalência da fitase

The objective of this work was to evaluate the use of equivalency values of phytase as a basis for reduction of available phosphorus (aP) in broiler diets. Ten nutritional programs were evaluated with six replicates of 15 birds each. The following were evaluated: performance, tibia ash content, and feed costs. From 1 to 7 and 36 to 42 days of age, the birds received basal diet; from 8 to 21 days, diet without phytase containing 3.9 g kg-1 aP and four diets with phytase containing from 1.1 to 2.5 g kg-1 aP; and from 22 to 35 days, diet without phytase containing 3.4 g kg-1 aP plus diet with phytase containing 1.6 g kg-1 aP. The best nutritional plan was formed by the diets: 4.7 g kg-1 aP without phytase (1 to 7 days); 2.0 g kg-1 aP supplemented with phytase (8 to 21 days); 3.4 g kg-1 aP in feed without phytase (22 to 35 days); and 3.0 g kg-1 aP in feed without phytase (36 to 42 days). The reduction of aP occurs in the period from 8 to 21 days of age and corresponds to 2.0 g kg-1 of feed supplemented with phytase.