Evaluation of phytase products on performance and bone mineralization in low non-phytate phosphorus corn and soybean meal-based broiler starter diets

Summary: The objective of this study was to evaluate corn/soybean meal-based starter diets that exclude inorganic P or contain low non-phytate phosphorous with phytase supplementation on bird performance, bone mineralization, and the effect on dicalcium phosphate equivalency. A PC and four NC treatments with graded levels of nPP were used to create a standard curve of increasing nPP levels. Phytase A was added to the NC1 (no DCP, nPP= 0.13 %) at 1,500 FTU/kg and 2,000FTU/kg (to overcome the low nPP value). Phytases A, B, and C were added to the NC2 (nPP=0.22 %) at 1,500FTU/kg to provide a commercially available phytase product comparison. Phytase A was also added to the PC (nPP= 0.5 %) at 1,500 FTU/ kg. Linear and quadratic regressions using SAS PROC REG were conducted to determine impacts of increasing levels of nPP. The NC1 and NC2 nPP level in a broiler starter mash diet decreased bird performance and bone parameters relative to a similar Ca:nPP ratio of the PC diet (0.95:0.5, P < 0.05). A 1,500 FTU/kg inclusion of phytase A increased LWG, IBW, Pen FI, and tibia mineralization when compared to a 0.22 % nPP NC2 diet or NC2 diet containing either phytase B or C (P < 0.05). Mortality for this study was not significant despite the low nPP level (P > 0.05). The addition of phytase products to diets was not able to overcome nutrient detriment in inorganic phosphate free diets and varied in effectiveness in 0.22 % nPP diets.