THE EFFECTS OF DIETARY POLY-B-HYDROXYBUTYRATE ON GROWTH, FEED UTILIZATION, AND SURVIVAL OF NILE TILAPIA (OREOCHROMIS NILOTICUS) FRY

摘要

Poly-beta-hydroxybutyrate (PHB) is a natural polymer that is intracellularly accumulated as a carbon and energy reserve by a wide variety of bacteria and can be depolymerised into water-soluble short-chain fatty acid (SCFA) monomers. It has shown thepotential to be used as an alternative anti-infective strategy for aquaculture rearing (De Schryver et al., 2009). Several studies on PHB were performed using different aquaculture species such as European sea bass Dicen-trarchus labrax juveniles (De Schryver et al., 2009), giant river prawn Macro-brachium rosenbergii larvae (Nhan et al., 2010), and Siberian sturgeon Acipenser baerii juveniles (Najdegerami et al., 2011). Results indicated that PHB increases the weight gain, survival, and SCFA concentration in the gastrointestinal tract. TCBS counts as a measure for Vibrio spp. were found to be significantly lower in PHB treated giant river prawn, indicating that the PHB addition also had a growth inhibitory effect towards these potentially pathogenic microorganisms. However, further research is needed in order to determine the exact mode of action. As there is only limited information on PHB function as an ingredient in fish starter diets, the present study was conducted to assess the potential effects of several dietary levels of PHB on feed utilization, survival and growth of Nile tilapia Oreochromis niloticus fry.