Manufacturing pellets with different binders: effect on water stability and feeding response in juvenile Cherax albidus.

In this study, we used natural polysaccharides (pectin, alginate and chitosan) as binders to generate pellets 23 for crayfish feeding. Pellets were produced by cold extrusion in order to preserve nutrients from degradation 24 and reduce energy consumption. Thereafter, pellets were submitted to a coating procedure, with the aim of 25 improving pellet stability inwater. Pelletwater stabilitywas analyzed bymonitoring the diameter of the released 26 particles in water over progressive time intervals up to 24 h, employing a Low Angle Laser Light Scattering 27 Technique. Alginate containing pellets released particles with a smaller diameter than chitosan and pectin 28 containing pellets, indicating that alginate containing pellets disaggregated more and therefore were less 29 stable in water than the other pellet types. The effects of the different polysaccharide containing pellets 30 were evaluated on crayfish feeding response employing juvenile Cherax albidus. The feeding experiment 31 was carried out for 12 weeks, at the end of which growth parameters and the activity of amylase, lipases and 32 proteases in the gastric juice, hepatopancreas and intestine were recorded. Crayfish fed pectin containing 33 pellets exhibited a significant weight gain. Digestive enzyme activities did not statistically show significant 34 differences in the digestive tract except for amylase that was significantly higher in the intestine of animals 35 fed pectin containing pellets. Our data indicate that pectin and chitosan pellets showed the best water stability 36 performances, moreover pectin pellets brought about the highest body weight gain and affected the amylase 37 profile in the intestine of juvenile Cherax albidus.