Effect of fermented fish silage in diets for juvenile Piaractus brachypomus on growth performance, blood parameters and meat quality

ABSTRACT Fermented fish silage (FFS) produced from processing waste of the main fishery species in the Amazon could serve as an alternative with a circular economy approach. We determined the dietary effect of FFS as a replacement of fishmeal on growth performance, blood parameters and meat quality of juvenile Piaractus brachypomus (58.6 ± 7.4 g). FFS was prepared by mixing local raw materials (70% fish waste, 7.5% molasses, 3.75% papaya, 3.75% pineapple, 15% yogurt) and fermented for nine days. Five isonitrogenous (278 g kg-1 CP) and isocaloric (4,262.21 kcal GE kg-1) diets were formulated with an increasing percentual replacement of fishmeal by FFS (0, 25, 50, 75, 100%). Piaractus brachypomus were kept in cages in a pond (three replicates per FFS level) and fed for 90 days at a 4% body weight-feeding rate. No pellet refusal nor mortality was registered. Growth performance was not affected by FFS replacement, except for the hepatosomatic index, which was higher in fish fed 100% FFS (2.84 ± 0.51). Blood parameters and meat pH (6.10 ± 0.78) did not vary significantly and samples of fish meat did not exceed the maximum permissible limits for total aerobic mesophyll, Escherichia coli, Staphylococcus aureus and Salmonella spp. The highest total protein and ash content in meat were observed in fish fed 100% FFS, followed by 75% FFS, both groups also presenting the second highest values of total lipid content. We conclude that FFS represents a safe alternative for replacing fishmeal in extruded diets for juvenile P. brachypomus.