Organic acids as a functional feed additive in the commercial feeds of tilapia and marine shrimp

It is common practice in the aquaculture industry to use large amounts of antibiotics following the discovery of its growth promoting and disease fighting capabilities. In view of the current greater restrictions or ban on antibiotic use, there is a critical need to evaluate alternatives. One potential substitute for antibiotic growth promoters in feeds is organic acids. Organic acids such as benzoic, formic, lactic and propionic acids have traditionally been used as storage preservatives for food and feed ingredients due to their antimicrobial properties. Even though organic acids are used extensively in the feeds of livestock, not much is known about the beneficial effects of these functional additives in aquaculture feeds.

Several laboratory-based feeding trials were conducted on white shrimp (Litopenaeus vannamei), freshwater prawn (Macrobrachium rosenbergii) and various tilapia strains (Oreochromis spp.). Proof of concept was established for dietary organic acids in their beneficial impact on the growth performance, nutrient utilization, immune response and disease resistance of these farmed aquatic animals. Due to these encouraging laboratory results, a pre-commercialization technology grant was awarded by the Malaysian government to develop a prototype organic acids product for use in aquafeeds as an alternative to antibiotics. In collaboration with Sunzen Feedtech Ltd., a pilot plant was constructed in 2012 to produce a novel microencapsulated organic acids blend using centrifugal spray cooling technology. Organic acids were spray-chilled with a unique lipid coating for slow release in the gut of the farmed aquatic animal and this new product is called Orgacids™-AQUA.

In collaboration with Gold Coin Specialities Ltd., a major Asian multinational shrimp feed producer, we conducted a field trial in a commercial tiger shrimp farm. The commercially manufactured shrimp feeds contained either no added Orgacids or 2% Orgacids. The mean total bacterial count and Vibrio spp. count in the pond water of shrimp fed the 2% Orgacids feed were generally lower compared to the control pond. Disease challenge tests with Vibrio harveyi showed that shrimp fed the organic acid supplemented feeds had significantly higher survival due to enhanced immune response and less hepatopancreatic damage. Nutrient utilization was enhanced and Vibrio counts were lowered in the hepatopancreas and gut of shrimp fed the Orgacids feed.

In collaboration with Cargill Feed Ltd., a field trial was conducted with Nile tilapia in a large commercial tilapia farm. Duplicate cages of tilapia were fed starter and grower feeds without any added organic acids or 2% Orgacids-AQUA. Total fish mortality in cages fed the organic acids added feeds were lower despite less antibiotics being used compared to the control cages. The immune response of tilapia fed the organic acids added feeds was significantly enhanced. 

The potential growth promoting efficacy of dietary organic acids in shrimp and tilapia is encouraging. The ability of organic acids to protect shrimp and tilapia from vibriosis and streptococcal infections, respectively, is a new discovery.

Professor Wing-Keong Ng

Professor Wing-Keong Ng received his Masters degree in Aquaculture from the Asian Institute of Technology (Thailand), PhD in Nutrition from the University of California (Davis, USA) and a post-doctoral fellowship at Mississippi State  University (USA). He has been a Visiting  Scientist to the University of Stirling (Scotland, UK) and the University of Tasmania and CSIRO (Australia).  Currently he is a Professor with Universiti Sains Malaysia. He has published extensively in the area of aquaculture nutrition and is on the editorial board of several international and regional journals.  He is an active consultant to various international aquaculture organizations and aquafeed-related companies.