Comparative studies on composition of feed additives for juvenile fish produced with bioconversion of fish raw materials

Abstract

Technology of feed additive for fry feeding in fish farms is developed to provide both important nutrients (proteins, lipids, etc.) and optimal peptide composition of protein that is achieved using proteolysis of raw materials under certain conditions. For this purpose, enzymatic hydrolysis of substandard small-sized frozen pollock was used. The rational duration of the hydrolysis process was 60 min. that provided the degree of protein hydrolysis of 26–28 %. The experimental fermentolysate was concentrated to a water content of 3–4 % and presented as a feed additive TINRO-60. This product is compared with other feed additives (dried fermentolysates) produced in Russia from fish raw materials using bioconversion, such as Biomarin, Bioprom and Vakhob. General chemical composition of tested products was determined by standard methods of analytical chemistry; composition and content of fatty acids — by gas-liquid chromatography; microand macroelements, as well as toxic metals — by atomic absorption spectrophotometry; fractional composition of proteins and peptides — by high pressure gel permeation chromatography; amino acid composition — by ion exchange chromatography on a high-speed analyzer. All tested samples contain similar amount of the main feed component — protein substances. The quantitative ratio of peptide fractions is also comparable, the sum of the most active fractions (MW 0.1−10.0 kDa) in TINRO-60 and Biomarin is close to their level in tissues of Artemia, natural food for fish fry. The content of essential amino acids, EPA and DHA is significant in Biomarin, TINRO-60 and Bioprom, but almost twice lower in Vakhob. Analysis of mineral composition showed that bioconversion into dry fermentolysates does not cause concentration of toxic elements. High quality of the protein feed additive TINRO-60 produced by bioconversion of nonstandard fish raw materials under certain conditions is proved.