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• In this study, the apparent digestibility of protein and amino acids of  ten types of plant and animal feed ingredients as the main sources of protein was evaluated in Siberian sturgeon diet (290-250 g).

Materials and Methods: Feedstuffs included fish meal, meat and bone meal, poultry byproduct meal, blood meal, feather meal, soybean meal, rapeseed meal, wheat gluten, corn gluten and bakery yeast. The dietary treatments included: reference diet and ten different experimental rations (30% of the target feed ingredient + 70% of the reference diet). Chromic oxide was used as an indigestible marker in dietary feed. A group of 165 Siberian sturgeons stocked into 33 tanks with 500 liters volume and fed with test diets (3 replicates per diet).

• At the end of the experiment, the highest and lowest protein digestibility was observed in fish meal (92.87%) and poultry byproduct meal (59.96%), respectively. Also, the highest level of amino acid digestibility in fish meal was measured (90.9% and 88.13% for total essential and non-essential amino acids respectively). The lowest digestibility of the essential amino acids was observed in rapeseed meal (65.5%) and non-essential amino acids in poultry powder (60.68%). Conclusion: Based on the results of the present study, fishmeal, meat and bone meal, poultry byproduct meal, corn gluten and wheat gluten were identified as feed ingredients with high protein and amino acids digestibility for Siberian sturgeon.