Feed intake and gene expression of appetite-regulating hormones in Salminus brasiliensis fed diets containing soy protein concentrate.

Dourado (Salminus brasiliensis) is a large carnivorous fish with high commercial value for which sustainable aquaculture relies on the substitution of expensive dietary animal protein sources in aquafeeds, in particular fish meal (FM), by cheaper plant protein, such as soy protein concentrate (SPC). This study aimed at evaluating feed intake and gene expression of appetite- regulating hormones [orexin, cocaine and amphetamine regulated transcript (CART), leptin, cholecystokinin (CCK) and peptide YY (PYY)] in the intestine, pyloric caeca and hypothalamus of juvenile dourado fed diets containing graded levels of SPC and FM as dietary protein sources for a period of three weeks. Increasing dietary plant protein contents reduced daily feed consumption and the expressions of the anorexigenic hormone CCK in the anterior intestine and in pyloric caeca and PYY in pyloric caeca. No changes were detected in the hypothalamic expression of appetite-regulating hormones, suggesting that gastrointestinal hormones are more involved in the decrease in feeding induced by plant protein diets than central appetite-regulating systems.