Production and economics of probiotics treated Macrobrachium rosenbergii at different stocking densities

The effect of stocking density on growth, production, feed utilization and condition factor of probiotic treated Macrobrachium rosenbergii were analyzed in the present study. Juvenile prawn of weight 3.48 +/- 1.4 g was stocked at the densities of 2, 3, 4 and 5 individuals/m(2) respectively in T1, T2, T3 and T4. A supplementary diet containing 32% protein was used with the commercial feed probiotics Zymetin daily and soil probiotics Super PS weekly. After 180-days culture-period, significant differences in growth parameters were observed between different treatments (F-3,F-645 = 228.81, P < 0.01). The highest and lowest final mean body weight (56.95 +/- 6.7 g and 30.85 +/- 11.43 g), weight gain (47.47 +/- 6.74 g and 27.37 +/- 11.43 g), specific growth rate (1.49 +/- 0.07% BW/day and 1.18 +/- 0.19% BW/day), and survival rate (88.43 +/- 0.46% and 69.23 +/- 0.32%) were found in T1 and T4, respectively. The treatments containing lower stocking densities showed better feed utilization indices; and except T4, higher stocking densities showed better gross production. The length-weight analysis showed positive allometry in T1, T2 and T3; whereas, it was isometric in T4. The condition factors varied between 0.80 and 1.16 indicating the healthy condition of the prawns in all groups. Water quality parameters were found within the acceptable limits in all treatments. Probiotic treated prawn cultured with the density of 3/m(2) obtained highest gross return, and net returns to land, family labor and management, would be considered for the best practice of commercial prawn production.