Superdosing of bacterial phytase (EC 3.1.3.26) in broiler diets with reduced levels of digestible amino acids

Abstract The aim was evaluating the effect of phytase superdosing in diets with reduced amino acid levels (methionine, lysine, threonine) for broiler chickens from 1 to 45 days. Parameters related to performance, carcass characteristics, intestinal morphometry, and ileal digestibility was evaluated. Were used 1848 male Cobb 500 broilers with 46 g ± 0.02 g of starter weight, divided into 12 treatments, in a completely randomized design in a 3 × 4 factorial arrangement (3 nutrient matrices: 0 (control), 5 (-5%), and 10% (-10%) of reduction in the levels of the digestible amino acids and 4 levels of phytase (0, 500, 1500, and 3000 FTU/kg), 7 replicates of 22 birds per experimental unit. For ileal digestibility another trial was carried out following the same experimental design; with 252 animals 12 treatments, 3 replicates of 7 birds each. Analysis of variance of the data was performed, and regression analysis was used for the FTU levels. For the nutrient matrices, Tukey's test was used at the 5% probability level. The results show that, after phytase supplementation at 1500 FTU/kg, is possible a reduction by up to 10% of the levels of the top three limiting amino acids in relation to control level for broilers from 1 to 45 days of age without affecting the productive performance of the animals. The superdosing of phytase promoted a greater availability of phosphorus, increasing the villus: crypt ratio, villus area. A reduction in dietary Ca and P levels is recommended, increasing the availability of these minerals through the enzyme matrix and supplementation with 1500 FTU/kg of bacterial phytase.