Songklanakarin Journal of Science and Technology (SJST) (Mar 2004)
Effects of phytase enzyme and inorganic phosphate on the utilization of phosphorus in sex reversed tilapia (Oreochromis niloticus Linn.)
Abstract
The effects of feed-supplemented phytase were studied in 3.39-6.49 g sex-reversed tilapia. A total of eight formulated feeds were given to the fish, among which formulae 1-5 were phytase-supplemented at 0, 500, 1,000, 2,000 and 4,000 FTU / kg diet while in formulae 6-8, 0.46% inorganic phosphate from one of three sources, namely mono-calcium phosphate, di- calcium phosphate and tri-calcium phosphate, was supplemented. A 60-d period feeding trial was carried out in 200-l glass tanks. The best growth performance and feed utilization were recorded in tilapia given the feed with 4,000 FTU supplemented phytase / kg diet. It was further noted that the supplementation of 1,000 FTU / kg diet was sufficient to achieve satisfactory phosphorus digestibility, blood parameters and bone phosphorus contents. The phosphorus content in the feces could be reduced by replacing the inorganic phosphate from three sources with 2,000 or 4,000 FTU supplemented phytase / kg diet. The supplementation of phosphate from three sources made no significant differences in growth, feed efficiency or fecal phosphorus.
