Nutrient balance of layers fed diets with different calcium levels and the inclusion of phytase and/or sodium butyrate

in this study, hisex brown layers in lay were evaluated between 40 and 44 weeks of age to evaluate the inclusion of bacterial phytase (ph) and sodium butyrate (sb) to diets containing different calcium levels (cal). performance, average egg weight and eggshell percentage, in addition to nutrient metabolizability and ca and p balance were evaluated for 28 days. birds were distributed according to a completely randomized experimental design with a 3x2x2 factorial arrangement, with three calcium levels (2.8, 3.3, 3.8%); the addition or not of phytase (500phu/kg) and the addition or not of sodium butyrate (20meq/kg), composing 12 treatments with eight replicates of one bird each. there was no additive effect of phytase or sb on the evaluated responses. feed intake and feed conversion ratio were influenced by cal, with the best performance obtained with 3.3% dietary ca. ca balance was positively affected by dietary ca, and p balance by the addition of phytase. ca dietary concentration, estimated to obtain ca body balance, was 3.41%, corresponding to an apparent retention of 59.9% of ca intake.