Dietary effects of Azolla pinnata combined with exogenous digestive enzyme (Digestin™) on growth and nutrients utilization of freshwater prawn, Macrobrachium rosenbergii (de Man 1879)

The present study was conducted to evaluate the effect of either individual or combined wheat bran (WB) replacement with Azolla pinnata supplemented with Digestin (TM) in the diet of freshwater prawn, Macrobrachium rosenbergii Postlarvae (PL) on growth performance, nutrient utilization, chemical body composition and survival (%). Experimental diets were a wheat bran-soybean based diet with no Azolla and Digestin TM (control, T-1), and diets containing 17% Azolla supplemented with Digestin (TM) 0% (T-2), 1% (T-3), 2% (T-4) and 3% (T-5). Each experimental diet was allocated into three tanks (6 m(3) /tank) fed for 12 wks. Each tank was subdivided into three equal pens by nets (2 m(3)) and stoked with 84 PL/m(2). The experimental diets were readily consumed by prawns PLs where both high growth and good feed efficiency were achieved for all diets. The results showed that the diets containing A. pinnata supplemented with Digestin (TM) at the level up to 3% have the higher growth and better nutrient utilization than the control diet. No differences were observed for moisture and protein content among the experimental diets. However, the highest protein content was observed on prawns fed on diets T-1 and T-5 respectively, while the lowest value was recorded for T-4 diet. The results also show that prawn PLs fed the diets contain A. pinnata and supplemented with Digestin (TM) recorded the highest values of body lipid content compared to the control diet. Feed efficiency and economic conversion rate (ECR) values show that economic performance and the cost-effectiveness of the A. pinnata supplemented with up to 3% Digestin (TM) recorded the highest net return, and therefore it is recommended for prawn, M. rosenbergii PL's. These results are clearly indicating that A. pinnata have a good potential for use in prawn diets at reasonable levels than other conventional diets.