Growth and economic analysis of freshwater prawn,Macrobrachium rosenbergii(de Man), produced with feeds substituting sunflower cake for fish meal, soya bean meal and mustard oil cake

Abstract

A feeding trial with Macrobrachium rosenbergii was carried out to test the effectiveness of sunflower cake (SFC) as a replacement for conventional protein sources. Four isonitrogenous (~30% crude protein) and isocaloric (388–402 kcal) diets were formulated. Diet-1 was a control made with conventional ingredients including fish meal, soya bean meal and mustard oil cake. Diet-2, Diet-3 and Diet-4 were made with 30%, 40% and 50% SFC, respectively, replacing the usual protein sources used in Diet-1. After 100 days, diets with SFC inclusion showed favourable growth and economic performance trends compared to control diet-1, but without significant differences (p > .05). Better production (572.89 ± 62.99 kg/ha) was observed with Diet-4 followed by Diet-2, Diet-3 and Diet-1. Diet-4 revealed the best feed conversion ratio (2.56 ± 0.24), specific growth rate (1.18 ± 0.05) and protein efficiency ratio (1.14 ± 0.10) among these diets. Whole carcass composition analysis revealed highest crude protein (18.19%) and lipid (4.43%) content in prawns fed Diet-3 followed by Diet-4. Highest total income, gross margin and benefit cost ratio (BCR) per hectare from prawns were US$5,759, US$2,623 and 1.84, respectively, found in Diet-4. This study demonstrates that 30%–50% inclusion of SFC has favourable impacts on productivity and profitability compared with controls, with 50% SFC inclusion as the most cost-effective diet for prawns without apparent compromise in growth, flesh quality or economics. The performances of the diets suggest that SFC may be a suitable substitute for fishmeal, soya bean meal and mustard oil cake in prawn feed. The effectiveness of higher SFC concentrations should also be investigated.