A novel consensus bacterial 6-phytase variant totally replaced supplemental inorganic phosphate from one day of age in both male and female broilers.

1. This study tested the capacity of a novel consensus bacterial 6-phytase variant (PhyG) to totally replace dietary supplemental inorganic phosphate (Pi) in broilers from one day of age, using a phased dosing strategy for the phytase and a phased reduction in phytate content of the diet. A 2x2 factorial arrangement including two treatments and two genders was used.2. A total of 1,248, one-day-old Ross 308 broilers were assigned to 24 floor pens (52 birds/pen). Two treatments included: 1) a positive control diet (PC) based on mixed grains and oilseed meals, containing inorganic phosphorus (Pi) from monocalcium phosphate (MCP) and 2,000 XU/kg xylanase, and; 2) an inorganic P free (IPF) diet reformulated without Pi, reduced in Ca (-2.0 g/kg) vs. PC and supplemented with PhyG at 3,000 FTU/kg in starter (d 0 to 11, 3.4 g/kg phytate-P (PP)), 2,000 FTU/kg in grower (d 11 to 22, 3.3 g/kg PP), and 1,000 FTU/kg in finisher 1 (d 22 to d 35, 2.9 g/kg PP) and finisher 2 (d 35 to d 42, 2.8 g/kg PP) phase. Each treatment was assigned to 12 pens, with six pens containing males and six containing females. Tibia samples were collected on d 11, 22 and 42 from two birds per pen.3. The IPF treatment maintained or improved ADG, ADFI and FCR compared to PC in all feed phases. IPF increased BW at 42 days of age by 3.97% (P<0.01) and ADG from d 0 to 42 by 4.10% (P<0.01), and reduced corresponding FCR by 1.5 points (P<0.05), respectively, vs. PC. Males exhibited higher BW, ADG and ADFI than females from 11 d of age onwards (P<0.05). An interaction (P<0.05) between treatment and gender was observed for FCR (d 0 to 22, d 0 to 42) and FCRc (body weight corrected FCR, d 0 to 42), whereby IPF treatment reduced (P<0.05) FCR vs. PC in males but not in females. Tibia ash from birds fed IPF was equivalent to PC at 11, 22 and 42 d of age and did not differ between males and females.4.The data demonstrated that the phytase, when applied in a phased dosing-regimen to broiler diets with a graded reduction in phytate-P content, was effective in totally replacing Pi during all growth phases, as determined by performance and tibia ash from both males and females.