Effect of dietary phosphorus, calcium, and phytase on performance of growing turkeys

Female and male turkeys were fed 110, 73, 52, and 30% of the NRC (1994) non phytate P (NPP) requirement without and with 500 phytase units (FTU)/ kg du ring 4 to 14 or 16 wk of age, respectively. At 110% P (control; also 110% o f NRC Ca), phytase was without effect. At 73% of NPP (100% Ca), without phy tase, performance was similar to the control; with phytase, performance was equivalent, and in some stages, superior to the-control. At 52% of NPP (90 % Ca), performance was inferior,without phytase and was variably similar or poorer than the control with phytase. At 30% NPP without phytase, poults g ained poorly and showed a high incidence of leg disorder at 8 wk when they were removed from experiment; poults gained better with 80% NRC Ca compared with 110%. At 30% NPP with phytase, turkeys performed remarkably well, alt hough suboptimally, at 80 or 110% NRC Ca. Phytase at 400, 300, and 200 FTU/ kg with increasing age periods performed as well as 500 FTU/kg with 73% of NRC NPP (100% Ca) and 52% NRC NPP (90% Ca). These lower phytase levels were not as sufficient as 500 FTU/kg with 30% of NRC NPP; this inadequacy was m ore severe with higher dietary calcium. Phytase was effective in reducing d ietary P requirements of growing turkeys when the NPP levels were below NRC (1994) requirements.