EFFECT OF PHYTASE SUPPLEMENTATION IN SOYBEAN MEAL BASED DIET ON NUTRIENT DIGESTIBILITY AND GROWTH PERFORMANCE OF GREEN CATFISH (Hemibagrus nemurus)

摘要

Normal 0 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable{mso-style-name:"Table Normal";mso-tstyle-rowband-size:0;mso-tstyle-colband-size:0;mso-style-noshow:yes;mso-style-parent:"";mso-padding-alt:0cm 5.4pt 0cm 5.4pt;mso-para-margin:0cm;mso-para-margin-bottom:.0001pt;mso-pagination:widow-orphan;font-size:10.0pt;font-family:"Times New Roman";mso-ansi-language:#0400;mso-fareast-language:#0400;mso-bidi-language:#0400;} This experiment was conducted to evaluate the effect of phytase supplemented to the diet on phosphorus (P) digestibility and growth performance of the green catfish Hemibagrus nemurus . Five kinds of experimental diets were used in this experiment, namely diets A, B, C, D and E. Diet A, as a control, was supplemented with inorganic P, without phytase supplementation. Diet B, C, D and E were supplemented with 0, 20, 40 and 60 mg phytase/100 g soybean meal (SBM), respectively, without inorganic P supplementation. Fifteen fish with initial body weight of 6.9 + 0.2 g were stocked into each 60-l aquarium. Fish were fed on the diets for 60 days. Results indicated that P digestibility increased from 64.5% to 87.0% as phytase supplement increased from 0 mg in diet B to 60 mg phytase/100 g SBM in diet E. P digestibility in diet E was higher than that in diet A (77.6%). The daily growth rate and feed conversion ratio followed similar trend. P, Calcium (Ca) and Zinc (Zn) concentration in the whole body and bone of fish fed diet E were higher than the fish fed diet B, C and D, but were insignificant compared to the fish fed diet A. Nitrogen (N) and P loading by fish fed diet E were, respectively, 76% and 20% lower than those in fish fed the control diet. It is concluded that the inclusion of 60 mg phytase/100 g SBM in the diet of the green catfish could replace the utilization of inorganic P increase the digestibility of the diet thereby resulting in increased growth rate and reduced excretion of P and N into the waters. ? Keywords : Hemibagrus nemurus, phytase, soybean meal, phosphorus.