Assessing the apparent digestibility coefficients of some important nutrients and energy in rendered animal protein ingredients in juvenile Ussuri Catfish <i>Pseudobagrus ussuriensis</i>

ABSTRACT Objective This study aimed to determine the apparent digestibility coefficients for rendered animal protein ingredients fed to juvenile Ussuri Catfish Pseudobagrus ussuriensis. Methods Fourteen diets containing different feedstuffs were created by blending a control diet (70%) with each test ingredient (30%) and using 0.5% chromic oxide as an indicator. Results Results showed that protein peptide meal and white fish meal had higher gross energy, crude protein, and amino acid availability values, whereas horsemeat and bonemeal and pet-food-grade poultry by-product meal had lower dry matter, crude protein, and amino acid availability values. Enzymatically treated feather meal had relatively good apparent protein digestibility but led to a lower availability of lysine, histidine, methionine, and tryptophan. Conclusions White fish meal and protein peptide meal were optimal protein sources for Ussuri Catfish. Porcine blood plasma meal, porcine blood cell meal, feed-grade poultry by-product meal, poultry by-product meal from China, poultry by-product meal from America, whole-egg meal, and hydrolyzed chicken liver meal are potentially viable substitutes for fish meal. Enzymatically treated feather meal supplemented with amino acids could be a suitable protein source. Horsemeat and bonemeal and pet-food-grade poultry by-product meal were less favorable alternatives.