Effect of dietary microbial phytase supplementation on growth and nutrient digestibility of Pangasius pangasius (Hamilton) fingerlings

A feeding trial was conducted for 60 days to study the effects of exogenous microbial phytase supplementation on the growth and nutrient digestibility of Pangasius pangasius fingerlings. Eight isocaloric and isoprotein experimental diets (35.67% crude protein and 3870 kcal kg(-1)) were prepared with graded levels of phytase, e.g., 0 (T-1), 150 (T-2), 250 (T-3), 350 (T-4), 500 (T-5), 1000 (T-6) and 2000 (T-7) FTU (phytase units) kg(-1). Three hundred and fifteen fingerlings of P. pangasius (1.97-2.05 g) were randomly distributed in seven treatments with three replicates each. Maximum weight gain (350.72%), specific growth rate (2.51%), protein efficiency ratio (2.1), apparent net protein utilization (27.85%), energy retention value (88.47%) and feed conversion efficiency were observed in T-5 group supplemented with 500 FTU phytase kg(-1) diet. Apparent dry matter and protein digestibility in phytase-supplemented groups were significantly (P<0.01) higher at a minimum supplement of 500 FTU kg(-1) or higher. Liver alkaline phosphatase activity increased significantly in treatment groups. Supplementation at 500 FTU kg(-1) of phytase is optimum in the diet of P. pangasius fingerlings.