Impact of fishmeal replacement with Arthrospira platensis on growth performance, body composition and digestive enzyme activities of the freshwater prawn, Macrobrachium rosenbergii

In this study, we assessed the suitable level of replacement of fishmeal with a blue green microalga, Arthrospira platensis in feed for the post larvae (PL) of the freshwater prawn, Macrobrachium rosenbergii by evaluating the growth performance, prawn proximate composition, feed utilization parameters and the activity of digestive enzymes. The prawns were fed 5 different diets: a control diet and 4 different diets containing A. platensis at various levels such as 25%, 50%, 75%, 100%. These diets were fed to the PL for 90 days in triplicates. The growth performance in terms of weight gain, specific growth rate and feed efficiency ratio were found significantly (P < 0.05) higher in the prawns fed with the 50% of A. platensis feed fed group. At this level of 50% replacement, the prawn proximate composition, such as total protein, amino acids, carbohydrates and lipid contents were significantly (P < 0.05) higher than the control. Similarly, feed utilization parameters, such as feeding rate, absorption rate and conversion rate were significantly (P < 0.05) higher than the control. Added to that, the activity of the digestive enzymes such as protease, amylase and lipase showed the same trend at the level of 50% replacement. The hierarchy of the growth performance in prawns corresponds to 50 > 25 > 75 > 100% replacement of fishmeal with A. platensis. These results concluded that a partial replacement of the fishmeal with A. platensis at the level of 50% is beneficial for the growth of prawn M. rosenbergii.