A total of 720 one-day-old male broiler chickens were randomly allotted into nine treatments to evaluate the effects of different levels of phytase (Phy, 0.0, 500, and 1000 FTU/kg) and benzoic acid (BA, 0.0, 0.5, and 1.0 g/kg) supplementation on performance, nutrients digestibility, tibia mineralisation, intestinal morphology and serum traits in broiler chickens fed nutrient deficient diets (NC). The experiment was done in a 33 factorial arrangements with a completely randomised design until 42 days of age. Body weight (BW), body weight gain (BWG), and feed conversion ratio (FCR) improved when Phy (at both levels) was added to NC diets (p .05). Phy at 1X and 2X increased serum P, decreased serum Ca and litter moisture content (1000 FTU/kg) at d 28 (p .05), Furthermore, Phy supplementation increased tibia length and ash content as well as apparent ileal digestibility of P and ileal villus height (VH) (p .05). Addition of BA at 0.5 g/kg to the diets increased litter moisture, serum Ca content, jejunal villus height and ileal villus width (VW) (p .05). However, the combination of Phy and BA supplementation decreased apparent ileal of Ca digestibility (at 2X), and increased VH/CD ratio of the jejunum (at 1X). In conclusion, Phy was effective in improving performance traits, bone mineralisation, apparent ileal nutrients digestibility, and intestinal morphology. BA had no impact on performance traits, bone mineralisation, and ileal nutrients digestibility but at recommended level (0.5 g/kg) increased VH and VW in the ileum and jejunum.
