Quintessence International

Texto completo: acesso restrito. p. 404-409Conclusive experimental data regarding different sources of supplemented microbial phytase in tilapia feed are very scarce. An experiment was conducted using plant based diets (24.5% soybean meal; 11.5% wheat gluten; 22.5% corn; 32.5% wheat) containing graded supply (500, 750, 1000, 1250 U/kg) of microbial phytase from two different sources (experimental phytase SP 1002; Ronozyme®P). Additionally, a negative control diet (0.41% total P; 0.15% non-phytate P; no phytase added) and a positive control diet (0.88% total P; 0.62% non-phytate P; no phytase added) were examined. Apparent nutrient digestibility (0.3% titanium dioxide as marker) was measured using six sedimentation systems (0.15 m3/system) with external sedimentation column. Triplicate groups of 10 fish (average BW 110 g) fed 3 times a day and feces collection was conducted within 4 h following each feeding period. Chyme of the proximal small intestine (hepatic loop) was sampled for measuring phytate P. In a subsequent study, blood sampling was conducted from the caudal peduncle vein (triplicates from 9 fish per diet; average BW 125 g) for monitoring of inorganic P concentration in plasma at 2, 4, 8 and 12 h following the last meal. Phytase supplementation significantly improved digestibility of protein, calcium and phosphorus. Disappearance of phytate P from the hepatic loop was significantly improved due to phytase SP 1002 and the course of inorganic plasma P concentration indicated superior release of phytate P from the plant based diet under study