Optimisation of treated Black Soldier Fly Larvae (BSFL) using acidic salt to improve protein digestibility of giant freshwater prawn (Macrobrachium rosenbergii) larvae

Abstract

The high cost of Artemia sp. and the shorter shelf life of egg custard as the major aquaculture feed for Macrobrachium rosenbergii are giving burden to aquaculture farmers in financial support and labour force. In most studies, BSFL has proved to successfully replace commercial animal feed which BSFL has similar amino acid (AA) profile as fish meal (FM). Application of pre-treated BSFL introduced as an alternative feed for M. rosenbergii might be potential. Pre-treatment of BSFL was carried out by mixing 2 different types of acidic salt, potassium dihydrogen phosphate (MKP), KH2PO4 and sodium dihydrogen phosphate (MSP), NaH2PO4. Three different concentrations of each acidic salt were used to treat BSFL (5 %, 10 % and 15 %). Treated BSFL which has the highest percentage of protein decreases were selected and further identified biochemical composition through proximate analysis. Next, treated BSFL were used to partially replaced skimmed milk powder with 25% BSFL, 50% BSFL, 75% BSFL and 100% BSFL as protein source and formulated with grade A chicken egg, 1% moringa and 1% turmeric. Physical properties on treated diets and formulated egg custards are identity to determine the suitable feed for M. rosenbergii larvae. BSFL which treated with 15% KH2PO4 has highest protein decrease which is 17.39 % compared to BSFL that treated with 5% NaH2PO4, 10% NaHPO4, 15% NaHPO4, 5% KH2PO4 and 10% KH2PO4 (5.16 %, 12.98 %, 16.72 %, 10.38 % and 15.22 %). In addition, egg custard with 100% BSFL has higher protein content which is 33.88 % compared to egg custard, egg custard with 25% BSFL, egg custard with 50% BSFL and egg custard with 75% BSFL (23.36 %, 27.88 %, 30.21 % and 32.66 %). It shows that the potential application of treated BSFL provides optimum nutrients to M. rosenbergii to replace current commercial feed.