Apparent digestibility coefficients (ADCs) of dry matter (ADC d ), crude protein (ADC p ), energy (ADC e ) and amino acids in selected feedstuffs were determined for juvenile Siberian sturgeon (8.38 ± 0.20 g). The tested feedstuffs were fishmeal (FM), meat and bone meal (MBM), poultry by-product meal, hydrolysed feather meal, fermented feather meal solvent-extracted cottonseed meal and soybean meal. ADCs were determined using a reference diet and test diets at 7 : 3 ratios with 5 g kg )1 chromic oxide (Cr 2 O 3 ) as an inert marker. Fish were reared in a recirculating system and fed to apparent satiation five times daily. Cr 2 O 3 in diets and faeces samples were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and aciddigestion colorimetry (AC) methods, respectively. The results showed that ICP-AES method was more accurate for Cr 2 O 3 determination than AC method, and the results determined by ICP-AES method were used in this study. ADC d and ADC p of seven tested ingredients were lowest for MBM (59.1 and 84.5%) and highest for FM (79.9 and 94.5%); ADC e of tested ingredients were from 71.8% for SECM to 93.2% for FM. ADCs of amino acid in test ingredients followed similar trend to the ADC p . The ADCs of individual amino acids varied from 61.6% (histidine in MBM) to 98.8% (valine in FM). KEY WORDS

Summary The additives AlCl3, CoCl2, Al(OH)3, Ca(OH)2, and NaAlO2 are added to water to regulate its pH value (pH = 2‐13) in this study. The effects of media on the aluminum‐water reaction are investigated. Up to an increase in temperature, the hydrogen generation rate in different media increases. H+, OH−, Cl−, or Co produced from the additive favors the initial removal of the oxide film and aluminum corrosion. Therefore, the initial hydrogen generation rate increases in acidic and alkaline media. The synergistic effect of the formed fresh Co and Cl− catalyzes aluminum‐water reactions. However, the amount of hydrogen decreases with increasing mass of CoCl2 because of agglomeration of the catalyst Co. The higher concentration of OH− ions aids hydrogen generation. However, the reaction rate became slow after the rapid consumption of OH−, when the concentration of OH− was relatively small. Hydrogen is quickly generated and Al is completely reacted upon following additions of Al due to the cooperation between H+, Cl−, OH− ions, and the formed Al(OH)3.