Partial substitution of fish meal with soybean protein concentrate and extracted rapeseed meal in the diet of sterlet (Acipenser ruthenus)

Studies were carried out on the possibility of replacing fish meal in the feeds for sterlet (initial body mass 15.9 +/- 1.73g) with protein sources of plant origin (concentrate of soybean protein, extracted rapeseed meal). Experimental feeds (40% of crude protein, GE - 19 MJ kg(-1)) were prepared by extrusion method. Growth tests (50 days) were carried out in flow-through tanks of 600 dm(3) capacity. During the growth tests, no significant differences were found in biomass gain, specific growth rate (SGR 2.84-3.03 % d(-1)) and feed conversion rate (FCR 1.32-1.41) as well as protein efficiency rate (PER 1.78-1.90). Sterlets obtaining feeds with inclusion of plant-originating protein were characterized by significantly lower (p<0.05) body contents of dry mass, protein, fat and ash in comparison with fish fed on diets based on animal protein. The studies indicated that feeds for sterlet juveniles, almost one half of the protein required can originate from vegetable components without major loss in conversion efficiency.