Digestibility of selected feedstuffs in subadult Caspian great sturgeon, Huso huso using settlement faecal collection and stripping methods

Apparent crude protein (ADC(CP)), crude fat (ADC(CF)) and gross energy (ADC(GE)) digestibility coefficients of several typical and novel feedstuffs were determined to be employed in the formulated diets of subadult beluga (17.70 +/- 0.234kg) diets via two faecal collection methods of settlement (SFCM) and stripping (StM). The tested feedstuffs included three fish meals, three terrestrial animal by-products, three plant protein concentrates, nine high-protein plant meals and three low plant protein meals. ADC(CP) values varied in different fish meals ranging from 89.5% for Mexican sardine meal to 93.2% for anchovy meal with SFCM. ADC(CP) values for plant protein concentrates ranged from 82.8% for wheat gluten meal to 92% for soy protein with SFCM. ADC(CP) ranged from 37.2% for whole wheat to 75.6% for spirulina meal with SFCM. ADC(GE) was lower in low-protein plant meals (64.1%) in comparison to high-protein plant meals (70.2%). Fish meals showed the highest ADC(CF) values. A significant (P<0.05) quadratic regression relation (r(2)=0.92) was observed among in vivo ADC(CP) of five feedstuff classes fed to beluga and in vitro ADC(CP). The differences among ADC values appear to be significantly related to the effects of feedstuffs and therefore diet and faecal collection methods.