Effects of fermented soybean meal and supplemental methionine and lysine on growth, digestibility, body composition, and amino acid composition of Beluga (Huso huso).

There is an increasing concern about using limited high-quality protein sources in the aquafeed industry. The alternative solution to this problem is cost-effective plant proteins such as soybean meal (SBM). However, it is better to improve plant protein-containing diets through processing and supplemental amino acids. This study aimed to examine the effects of fermented soybean meal (FSBM) and supplemental methionine and lysine (ML) in diets on growth, digestibility, and body and amino acid composition in Beluga (Huso huso). Two basal diets (490 g FM Kg-1) of fish meal (FM) and FM with ML (FM + ML) were replaced by 40%, 60%, and 80% of FSBM and FSBM + ML (FM, FSBM40, FSBM60, FSBM80, FM + ML, FSBM40 + ML, FSBM60 + ML and FSBM80 + ML; 444 g kg-1 crude protein and 19.77 MJ kg-1 gross energy). The diets were fed to triplicate groups of Beluga (394.6 ± 4.3 g) three times daily for 56 d. The results showed that Beluga fed 80% FSBM and FSBM + ML had lower growth and feed utilization. Moreover, Beluga-fed FSBM + ML performed poorer than those fed FSBM (P < 0.05). No interactions between fermented SBM and ML were observed in apparent digestibility coefficients (ADC) and body proximate composition except for ADC of crude lipid. ADC in Beluga fed 80% were less than other diets. Substitution of FSBM and FSBM + ML in diets significantly reduced dry matter, ash and crude lipid; Crude lipid increased in groups fed FSBM + ML (P < 0.05). FSBM and FSBM + ML in 60% had higher and lower total amino acids in muscle and feces (P < 0.05), respectively. Also, excreted total amino acids in feces increased with ML (P < 0.05). Generally, in Beluga, FSBM-containing diets showed better effects on growth, feed utilization, whole-body lipid, and muscle and fecal amino acids than those with FSBM + ML. Fermented SBM could be replaced up to 60%.