AVALIAÇÃO DE FITASES MICROBIANAS EM DIETAS DE

The objective of this study was to evaluate phytases from different microorganisms on performance, bone characteristics, excretion and digestibility of nutrients, as well as phosphorus bioavailability and costs. The standard curve method was used to obtain the phosphorus bioavailability in response of performance and bone mineralization. The study was divided in four trials. In the first study were evaluated phytases from Buttiauxella sp (A; expressed in Trichoderma reesei) and E. coli (B; expressed in S. pombe) origins. A total of 2,160 male day-old Cobb 500 chicks were distributed in a completely randomized design to nine treatments and eight replicates containing 30 birds each. The treatments were: T1 Positive Control (PC) – meeting all requirements of the birds; T2 Negative Control 1 (NC1) – reduction of 0.14% P and 0.13% Ca; T3 Negative Control 2 (NC2) reduction of 0.17% P and 0.16% Ca; T4 NC2 + phytase A (250 FTU/kg); T5 NC2 + phytase A (500 FTU/kg); T6 NC2 + phytase A (1000 FTU/kg); T7 NC2 + phytase B (250 FTU/kg); T8 NC2 + phytase B (500 FTU/kg); T9 NC2 + phytase B (1000 FTU/kg). Regressions were performed on performance data, bone mineralization and excretion of nutrients to determine the optimal level inclusion of each phytase. A second trial was conducted to evaluate the response of the inclusion of a new bacterial phytase (E. Coli) supplemented on diets meeting all requirements of the birds, or with nutritions reduction. A total of 896 male day-old Cobb 500 broilers were divided into 32 experimental units, each unit consisting of 28 birds. The design was completely randomized with four treatments and eight replications. The treatments were: Positive Control (PC) diet meeting the nutritional requirements of the birds; Negative Control (NC) – reduction of 100kcal ME/kg; 0.14% avP and 0.11% Ca; NC + Phy (500FTU/kg); PC + Phy (500FTU/kg). The third trial was conducted to evaluate the inclusion of E. coli phytase (expressed in Pichia pastoris). A total 1890 male day-old Cobb 500 chicks were assigned to six treatments and seven replicates with 45 birds each, distributed in a completely randomized design. The treatments were: Positive Control (PC) diet meeting the nutritional requirements of the birds; Negative Control (NC1) reduction of 0.06% avP; Negative Control 2 (NC2) reduction of 0.12% avP; NC2 + Phytase (120 FTU); NC2 + Phytase (180 FTU); NC2 + Phytase (240 FTU). At the fourth trial four phytases were compared, being two fungal (F1 and F2) and two bacterial (B1 and B2), supplemented in a corn and soybean meal based diets. A total of 2,205 male day-old Cobb 500 chicks were assigned to seven treatments and seven replicates containing 45 birds and were distributed in a completely randomized design. The treatments were: Positive Control (PC) diet meeting the nutritional requirements of the birds; Negative Control 1 (NC1) reduction of 0.06% avP; Negative Control 2 (NC2) reduction of 0.12% avP; NC2 + Fungal Phytase 1 (F1); NC2 + Fungal Phytase 2 (F2); NC2 + Bacterial Phytase 1 (B1); and NC2 + Bacterial Phytase 2 (B2). All phytases were included in the concentration of 500 FTU/kg. Exploratory multivariate analyzes of the data were performed. In the first study it was found that phytase derived from Buttiauxella sp have a higher efficiency for body weight gain and feed intake in concentrations around 500 FTU/kg, while E. Coli phytase acts better around 1000 FTU/kg. Both phytases decreased the content of total phosphorus and soluble phosphorus in litter. The bioavailability calculated based on ash content and body