Effects of phytase supplementation on apparent availability of Mg, Ca, Zn, Cu, Mn, and Fe of plant feedstuffs for Nile Tilapia

One hundred Nile tilapia juveniles (Oreochromis niloticus; BW = 100.0 +/- 5.0 g) were assigned to 10 experimental cages to evaluate the effects of phytase supplementation (0, 1,000, and 2,000 FTU/kg) on calcium (Ca), magnesium (Mg), zinc (Zn), Copper (Cu), iron (Fe) and manganese (Mn) availability of ten feedstuffs: five energetic (corn, extruded corn, wheat meal, rice meal and low-tannin sorghum) and five protein (extruded soybean, soybean meal, sunflower meal, cottonseed meal and corn gluten meal). As reference, an albumin and gelatin-based diet [with 0.10% chromic oxide (III) as external marker] was fed to the juveniles. Thirty-one diets (one reference and 30 based on all feedstuffs and increasing levels of phytase) were formulated to determine the coefficients of apparent availability of minerals (Mg, Cu, Zn and Mn). Phytase increased mineral availability in plant feedstuffs, that change according to its biological value and enzyme supplementation level.