Comparative evaluation of dietary protein levels and plant-animal protein ratios inMacrobrachium rosenbergii(de Man)

The effects of varying dietary protein level (200, 250, 300 and 350 g protein kg−1 diet) and plant : animal protein ratio (1 : 2, 1 : 1, 1 : 1.5 and 2 : 1) on growth of juvenile Macrobrachium rosenbergii (de Man) with approximately 0.27 g initial body weight were evaluated in two separate 30-days study using practical diets. Significantly lower survival rate was recorded in prawns fed a diet containing 200 g kg−1 dietary protein (66.67%) whilst 300 and 350 g kg−1 protein gave the highest survival (96.67%). Significant differences (P < 0.05) in feed conversion ratio and protein efficiency ratio were recorded among different dietary protein levels. The results of the study showed that highest growth rate and maximum utilization of protein were recorded in prawns fed 300 g kg−1 dietary protein and further increase in the dietary protein does not have any added advantage. There existed no statistically significant difference (P > 0.05) in the specific growth rate, protein efficiency ratio, weight gain and survival rate among the juveniles of M. rosenbergii fed varying plant–animal protein ratios at 300 g kg−1 protein. Better-feed conversion ratio was recorded in diets having a plant to animal protein ratio of 1 : 1 (2.62) followed by 1 : 1.5 (2.66), however there was no significant difference between them (P > 0.05). Based on the present study, it would be possible to replace animal protein by low-cost plant protein in prawn feed. Better growth performance in juveniles of M. rosenbergii can be achieved by the incorporation of equal proportions of plant and animal protein (A : P = 1) in the diet.