02035naa a2200277 a 450000100080000000500110000800800410001902200140006002400520007410000250012624501590015126000090031052011980031965000120151765000140152965000130154365000250155665000160158165000220159765000100161965000190162965300100164870000230165870000220168177300540170321320222021-05-26       2021    bl uuuu     u00u1 u    #d  a1678-992X7 ahttp://doi.org/10.1590/1678-992X-2020-02882DOI1 aFREITAS, L. E. L. de  aProtein to energy ratios and cost, performance, and ammonia excretion in juvenile jundiá (Rhamdia quelen), South American catfish.h[electronic resource]  c2021  aThe determination of nutritional requirements, based on diets administered in practice, considers physiological specificities and sustainability are essential to the development of suitable aquaculture technologies for novel fish species. The growth of jundiá (Rhamdia quelen Quoy and Gaimard) juveniles (31.54 ± 4.92 g) fed five diets comprising increasing levels of digestible protein (DP: 24, 29, 34, 39, and 44 %) and digestible energy (DE: 12.13, 13.39, 13.81, 14.64, and 15.06 MJ kg-1) with DP:DE ratios: 20, 22, 25, 27, and 29 g MJ k-1, respectively, was evaluated. Each diet was fed to three groups of 25 fish for 75 days. Regression analysis showed that the different DP:DE ratios affected both growth and economic performance as well as excretion of total ammonia nitrogen. Fish fed diets with DP:DE ratios between 22 and 27 g MJ k-1 achieved a higher daily weight gain, superior apparent net protein utilization, feed conversion rates, and lower feed costs. For the economically viable and environmentally friendly farming of jundiá juveniles in the initial grow-out stage (30 to 80 g average weight), the best DP:DE ratio was 25 g MJ K-1 DP:DE (34.05 % DP and 13.81 MJ kg-1 DE).  aCatfish  aExcretion  aNitrogen  aNutritional adequacy  aNitrogênio  aNutrição Animal  aPeixe  aRhamdia Quelen  aDP-DE1 aSILVA, T. S. de C.1 aFRACALOSSI, D. M.  tScientia Agricolagv.78, Suppl., e20200288, 2021.