Apparent Digestibility Coefficients of Seven Animal Protein Ingredients for Coho Salmon (Oncorhynchus kisutch)...

The present study determined the apparent digestibility coefficients (ADCs) of dry matter, nutrients, and energy in selected seven animal protein ingredients, including Peruvian fish meal (PFM), native fish meal (NFM), Antarctic krill meal (AKM), native shrimp meal (NSM), poultry by-product meal (PBPM), meat and bone meal (MBM), and hydrolyzed feather meal (HFM) for coho salmon (Oncorhynchus kisutch) post-smolts (initial body weight: 212.73 ± 5.15 g). Using yttrium oxide (Y₂O₃, 0.5 g/kg) as an inert marker, a reference diet was formulated to contain ~440 g/kg of crude protein and 200 g/kg of crude lipid, whereas the test diets were composed of the reference diet and one of the test ingredients at a ratio of 70:30. The dry matter ADCs of the test animal protein ingredients ranged from 65.14% to 83.77%. The ADC of energy followed a similar trend to that of dry matter (69.03%-87.52%). The crude protein and lipid in all the test ingredients were well digested by the post-smolts with ADCs ranging from 74.12% to 91.67% and 75.44% to 92.38%, respectively. The MBM and HFM had significantly (p < 0.05) lower amino acid ADCs than other animal protein ingredients, resulting in lower levels of protein digestion in these two terrestrial animal ingredients. The ADCs of phosphorus varied greatly among the animal protein ingredients, with the highest in PBPM (70.52%) and the significantly (p < 0.05) lowest in MBM (37.31%). These ADCs data suggest that PFM, NFM, AKM, NSM, and PBPM can be prioritized as high-quality protein sources and provide more accurate information for the nutrient and energy utilization of coho salmon.