Effect of Probiotics on the Growth Performance and Survival of Fresh Water Prawn ( Macrobrachium rosenbergii ) Fed on Formulated Diets Supplemented with Probiotics

Two experiments were conducted to study the effects of probiotic Biosyn-AQ (comprising Lactobacillus sp, Bifidobacterium and Streptococcus) on growth and survival of giant freshwater prawn, Macrobrachium rosenbergii fed on formulated diets containing probiotics. In experiment-1 (6 weeks), three different dietary treatments; Control diet without probiotics (Commercial feed with 42% Protein [P]) and two formulated diets with probiotics Biosyn-AQ and varying levels of protein; Diet-1 (probiotics 4 g/Kg of feed and 35% P) and Diet 2 (probiotics 4 g/Kg of feed and 33% P) were used in triplicate groups. Post larvae (PL) were stocked at a rate of 40PL/tank (60 cm ×30 cm ×30cm). Feeding was done at 10% of body weight per day and prawns were weighed every 2 weeks. At the end of the 1 experiment, Growth parameters; final lengths and st weights, length gain (1.83-1.99 cm), weight gain (0.62-0.70 g) and specific growth rate (2.21-2.30) of prawns showed no significant difference between treatments. Significantly lower feed conversion ratios (0.96±0.16, 1.18±0.18) and higher survival (80.00±10.89 %, 62.50±12.5 %) were recorded for control diet and diet-1 respectively. Feed costs for diet 1 and 2 were lower compared to the price of control diet. However, PL fed on diet-1 performed on par with PL fed on protein rich control diet in terms of better growth performance and selected as a basal diet for 2 experiment. In experiment-2 (4 weeks), Basal diet (35% crude protein) was nd prepared by the supplementation of probiotics at 3 different concentrations ie; 1%, 2% and 3% of the diet. Prawns were stocked at a rate of 20 juveniles / tank. Significantly higher length gain, weight gain, specific growth rate and survival rate were recorded for prawns fed on diets supplemented with 2% and 3% probiotics than those fed on diet supplemented with 1% probiotics fed group. On the other hand, diet with 2% probiotics performed statistically in par with diet with 3% probiotics. Therefore, 2% of probiotics was selected as an ideal concentration in terms of low cost and better growth performance. From both experiments, it can be concluded that diet-1 formulation supplemented with 2% probiotics Biosyn-AQ leads to better growth performance of prawns and can be suggested for promoting sustainable culture of M. rosenbergii under Sri Lankan conditions.