Effects of microbial phytase on growth performance, immune responses and phosphorus, zinc, iron utilization in grouper Epinephelus coioides fed diets rich in soybean meal

• Main Authors: Wei-Chun Man, 滿維鈞
• Other Authors: Houng-Yung Chen
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/84490572417186643340

碩士 === 國立中山大學 === 海洋生物研究所 === 94 === Two experiments were undertaken to assess the dietary effects of microbial phytase on growth performance, mineral utilization, and immune responses in groupers, Epinephelus coioides. Basal diet contained fish meal and soybean meal as protein source and no phosphorus supplement. In experiment I, test diets containing 0 (0.2% sodium phosphate was supplemented; 0+P), 200, 400, 600, 800 FTU phytase/ kg were assigned to triplicate tanks and were fed for 12wk. Fish fed diet containing 0+P or 400 FTU phytase/kg showed better weight gains. Supplementation of phytase had no effect on feed efficiency, body tissue proximate composition, vertebral ash, and vertebra and whole-body phosphorus concentrations. Phosphorus utilization was improved and excretion tended to reduce for fish fed diets containing 400 and 600 FTU phytase/kg than the other treatments. Experiment II evaluated the effects of phytase supplementation on utilization of phosphorus, zinc and iron, and relative immune responses of the groupers. Three diets were formulated base on the results of experiment 1 to contain 0, 0+P or 400 FTU phytase/kg. The results of the 8-wk feeding trial indicated that phosphorus, zinc and iron utilizations were higher for fish fed diet containing inorganic phosphorus (0+P) than the phytase-containing diet. Phytase supplementation did not significantly affect immune responses. The present results indicated that phytase at the dosage of 400 FTU/kg is a suitable level in grouper diets, which would increase utilization and lessen excretion of dietary phosphorus.