Cherax albidus Juveniles Fed Polysaccharide-Based Pellets: Rheological Behavior and Effect on Growth

In this study two algal polysaccharides, alginate and agar, chitosan from chitin, and one fruit extracted polysaccharide, pectin, have been used as binders to make solid pellets to be employed in intensive crayfish farming. We examined the performance of the pellets in water and their effect on crayfish growth. The kinetics of water absorption and solute leaching of the pellets were measured for up to 24 h. Recovered liquid was analyzed for the release of particles in water by a Low Angle Laser Light Scattering Technique. The pellets were stable in water up to 24 h, although the water stability of pectin based pellets and chitosan based pellets was greater than other pellets. At the same time, crayfish feeding response to each pellet type was monitored in growth experiments by testing diets containing similar concentrations of nutrients (proteins, lipids and carbohydrates) mixed with each of the different polysaccharides. The presence of polysaccharides positively affected crayfish growth. Indeed, animals fed these pellets showed a higher percentage growth when compared to control animals. The simple methodology used for making pellets, and the encouraging results obtained in this study, could be considered suitable parameters for people interested in crayfish farming under intensive conditions. [Keywords.-- aquaculture; Cherax albidus; food pellets; polysaccharides; rheological characteristics].