Dietary short-chain organic acids enhanced resistance to bacterial infection and hepatopancreatic structural integrity of the giant freshwater prawn, Macrobrachium rosenbergii

The use of short-chain organic acids in the diets of aquacultured animals as a prophylactic to bacterial pathogens is receiving increasing research and commercial interest. After giant freshwater prawns, Macrobrachium rosenbergii, were fed diets supplemented with formic (FA), citric (CA), lactic (LA), propionic acid (PA), an organic acid blend (OAB) at 1% or a control diet (no additives) for 6 weeks, the prawns were subjected to Vibrio harveyi challenge for 2 weeks. From all remaining prawns, the hepatopancreatic histopathology was examined. Results showed that the survival of prawns to V. harveyi challenge was significantly higher (P<0.05) when fed the LA diet, followed by the CA diet, than the other treatments. This was likely due to less bacterial-induced hepatopancreatic damage and higher energy reserves compared to those fed the other diets. This is the first report to compare the efficacy of different organic acids to a crustacean as well as showing hepatopancreatic protective properties to freshwater prawns when challenged with pathogenic bacteria. The present study indicated that dietary organic acids can be a viable alternative to the use of harmful antibiotics in the prawn farming industry.