Comparison of growth, carcass composition and fatty acid profile of Hediste diversicolor fed faeces and food of beluga (Huso huso) in open and semi-closed systems

In this study, growth, carcass composition and fatty acid profile were evaluated in Hediste diversicolor fed faeces and food of beluga in open and semi-closed systems. This research was carried out based on three treatments in three replicates consisting of treatment 1: Nereis worm fed by beluga wastewater and using recycling water (semi-closed), treatment 2: Nereis worm fed by beluga wastewater without recycling water (open) and treatment 3: Nereis worm fed by concentrated food. Results showed that growth indices and survival rate in worms fed by concentrated food were higher than in comparison with other treatments (P<0.05). The highest content of SPUFA and w-3/w-6 ratio were observed in Nereis worms fed concentrated food (P<0.05). Reared worms in semi-closed system had the maximum content of SMUFA and DHA/EPA ratio (P<0.05). Significant differences were recorded in protein and lipid of carcass and TSS contents of worm tanks outlet (P<0.05). According to the results, because of having high content of protein as well as suitable ratios of DHA/EPA and w-3/w-6, these worms have high nutritional value for sturgeons and shrimp broodstocks. Economically, because of the lack of expense on food, the worm can be exploited as secondary product.