Serum biochemistry, body composition and bone mineralization of juvenile Clarias gariepinus fed phytase-supplemented soyabean diets

Abstract

The effect of microbial phytase on phosphorus utilization by juvenile Clarias gariepinus was tested on two diets consisting of oil-extracted soyabean and full fat soyabean meal. Each of these diets was formulated to replace fish meal at 25%, 50%, 75%, and 100 % as basal controls (P0). Phytase was supplemented in another four groups of the diets at 250 FTU/g (P1), 500 FTU/g (P2), 750 FTU/g (P3) and 1000 FTU/g (P4), respectively. A total of 2132 fish (11.55±0.2g) were stocked in duplicate tanks (26 fish/tank) and fed the phytase diets at 3% body weight for 84 days. Result in trial 1 showed that whole body ash declined with increasing phytase compared to control (Tukey, P>0.05). Phytase supplementation increased serum phosphorus (250 FTU/g and 500 FTU/g). Total protein decreased with phytase (Tukey, P<0.05). Bone minerals declined significantly with phytase at all levels. In trial 2, there was no difference between phytase and control for serum parameters (Tukey, P>0.05). The highest ash and bone minerals were recorded for 250 FTU/g phytase (Tukey, P<0.05). In conclusion, the research showed 250 FTU/g improved phosphorus utilization in full fat soyabean, which may indicate higher phosphorus bioavailability compared to oil-extracted soyabean meal.

Keywords: Biochemistry, nutrition, plant protein, mineralization, Clarias gariepinus