So sánh ảnh hưởng của bổ sung Phytase và Dicalciphosphate trong thức ăn lên tăng trưởng, hiệu quả sử dụng thức ăn và Phospho của cá Tra giống (Pangasianodon hypophthalmus Sauvage, 1878)

Two experiments were conducted at Novus Aqua. Research Center, Nong Lam University, Ho Chi Minh City, Viet Nam to evaluate the effects of supplying an enzyme phytase (Cibenza–phos) on growth performances, feed utilization and phosphorus content of juvenile tra catfish. Six isonitrogenous (32% crude protein) and isolipidic (6% crude lipid) diets were prepared with graded levels of supplemental phytase (750 FTU/kg and 1500 FTU/kg) and di-calcium phosphate (DCP; 0%, 0.5%, 1.0% and 1.5%).

 

In the experiment 1, juvenile tra catfish (9.6  0.1 g) were randomly distributed in 48 fiberglass tanks (300L) attached in a recirculation system at a stocking density of 30 fish/tank. Each experimental diet was fed to 8 groups of fish to apparent satiation twice per day for 12 weeks. At the end of the feeding trial, fish fed the diets containing 1.5% DCP, 750 FTU/kg and 1500 FTU/kg had higher final body weight, weight gain and specific growth rate compared to those of fish fed the control and diet containing 0.5% DCP and 1.0% DCP (P <0.05). Lower feed conversion ratio and higher protein efficiency ratio, protein retention and phosphorus retention were observed in fish fed the diet containing 1500 FTU/kg diet.

 

In the experiment 2, tra catfish (initial body weight, 130  5 g) were randomly distributed in 18 fiberglass tanks (500L) at a stocking density of 25 fish per tank. Experimental diet containing 0.5% Cr2O3 as the inert marker was fed to three groups of fish to apparent satiation for 2 weeks. Feces were collected by dissection 4 h after the morning meal. Higher apparent digestibility coefficient (ADC) of phosphorus was observed in fish fed the diet containing 750 FTU/kg and 1500 FTU/kg diet.

 

The present results indicate that supplementation of phytase (Cibenza-phos) at concentrations of 750 FTU/kg and 1500 FTU/kg could improve growth, feed and phosphorus utilization of juvenile tra catfish fed the diets containing high level of plant protein sources and reduce effluent phosphorus into aquaculture farms.