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

Abstract

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, <em>Macrobrachium rosenbergii,</em> 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 <em>Vibrio harveyi</em> challenge for 2 weeks. From all remaining prawns, the hepatopancreatic histopathology was examined. Results showed that the survival of prawns to <em>V. harveyi</em> challenge was significantly higher (<em>P</em> < 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.