Glycerol derived from biodiesel can replace maize in diets for juvenile silver catfish (Rhamdia quelen).

The aim of the present study was to evaluate the effect of maize replacement by crude biodiesel-derived glycerol on the zootechnical performance, chemical carcass composition and blood parameters of silver catfish (Rhamdia quelen) juveniles. A total of 600 silver catfish juveniles were distributed in a completely randomized design with six treatments comprised of isoproteic and isoenergetic pelleted diets with six levels of glycerol replacing maize, and five replicates. The glycerol maize substitution significantly influenced (p < 0.05) the final weight, clean trunk production and headless carcass yield, with the highest values for both parameters observed in the 100% substitution treatment, significantly different compared to the 0% replacement treatment. Plasmatic calcium, alkaline phosphatase, glucose, total proteins, oxaloacetic and pyruvic glutamic transaminase concentrations were not influenced (p < 0.05) by the dietary treatments, nor were moisture, crude protein and mineral matter (p < 0.05). Crude glycerol can be included in up to 7.5% in juvenile silver catfish diets. Biodiesel-derived glycerol can, thus, successfully replace maize in juvenile silver catfish diets.