Past literature has supported the supplementation of 25-OHD3 into poultry diets to reduce leg issues and improve muscle accretion. In addition, exogenous feed enzymes are included into poultry diets to increase nutrient utilization. The first objective of this thesis was to determine the effects of different sources and levels 25-OHD3 supplementation on D0-53 Ross x Ross 708 male broiler performance, processing yield, tibia ash, serum Ca and 25-OHD3 status. Data demonstrated that 25-OHD3 supplementation into diets with Low VitD3 (165 IU/kg) can improve broiler performance compared to High VitD3 (2756 IU/kg). The second objective was to investigate the effects of varying phytase inclusion with different xylanase levels on D0-56 Ross x Ross 708 male broiler performance, processing yield and tibia ash. Data exhibited some performance benefit (D46 and D56) when utilizing phytase (1000 and 1500 FTU/kg) with 1500 EPU/kg xylanase and phytase (250 and 1500 FTU/kg) with 3000 EPU/kg xylanase.