Amino acid digestibility of animal protein ingredients for bullfrogs in different phases of post-metamorphic development

Abstract

The development of diets that economically and ecologically meet the requirements of bullfrogs (Lithobates catesbeianus) is important for frog farming. Therefore, the objective of this study was to determine the apparent digestibility coefficients for essential amino acids of eight animal feed ingredients (poultry byproduct meal, meat and bone meal, salmon byproduct meal, tilapia byproduct meal, spray-dried blood meal, powered red blood cells, feather meal and sardine meal) used in the diets of bullfrogs. Additionally, the limiting digestible amino acids were determined for each ingredient. Bullfrogs in different phases of post-metamorphic development were used: 810 animals in the early phase (mean weight: 40 ± 10 g), 405 animals in the growing phase (95 ± 15 g) and 243 animals in the finishing phase (175 ± 25 g). Poultry byproduct meal, salmon byproduct meal and blood meal exhibited the largest number of high apparent digestibility coefficients for essential amino acids (>70%) in the early, growing and finishing phases, respectively. The animal protein ingredients were well digested by the bullfrogs and could be used in practical diets for this species, respecting the limits of inclusion and digestibility values for each developmental phase.