Growth performance, health, and gene expression of appetite-regulating hormones in Dourado Salminus brasiliensis, fed vegetable-based diets supplemented with swine liver hydrolysate

Abstract

Hydrolysates of slaughtering plants by-products are among the most promising feedstuffs for aquafeed formulations, supplying diets with amino acids and small peptides which perform functions ranging from palatability enhancers to nutrient-rich ingredients to immunity modulators. This study evaluated growth performance, blood and immunological parameters, and gene expression of food intake-regulating hormones in juvenile dourado Salminus brasiliensis (Cuvier, 1816) (25.07 ± 3.9 g) fed vegetable-based diets supplemented with swine liver hydrolysate [SLH] (30, 60, 90, 120, 150, and 180 g kg−1). Hematological and immunological factors did not change for either vegetable- or swine liver hydrolysate-based diets. Feed consumption was improved in fish fed a diet containing 30 g kg−1 SLH, while 150 g kg−1 of inclusion improved growth performance. Results suggest an effect of feeds on cocaine and amphetamine regulated transcript (CART) expression, which had higher expression levels in the hypothalamus of fish fed the diet containing 150 g kg−1 of SLH. Cholecystokin (CCK) expression levels only increased in fish fed 60 g kg−1 SLH compared to the control diet, and this may be related to gastric tract filling rather than dietary peptides.