Photomicrograph of the histological structure of diaphysis of tibia in broiler chickens at 35 d of age showed cortical compact bone (C.b) with its osteons (os), medullary trabecular bone (T.B) with its bone trabeculae (red arrow), and bone marrow (black arrow). Hematoxylin and eosin stain (H & E, x40). (1), Positive control diet contained the recommended Ca and nPP; (2), negative control diet contained the recommended level of Ca and low nPP; (3), NC + 600 U phytase/kg of the diet; (4), NC + 0.05% multi-strain probiotic; (5), NC + 0.2% Saccharomyces cerevisiae; and (6), NC + 0.2% fumaric acid.