Burbot (Lota lota maculosa ) are the only true freshwater cod that hav e recently grown to become one of the most promising candidates for commercial aquaculture. This is because burbot have a high fecundity, suitable feed conversion, and fast growth rate. Burbot fillets are of high quality and their roe and liver are appreciated as delicacies. Additionally, burbot are resistant to most salmonid pathogens and require similar rearing conditions to trout production. Despite the numerous advantages and commercial benefits , there is limited understanding of nutritional (protein) requirements for burbot.To address this, a feeding trial was conducted to evaluate dietary protein requirements for sub-adult burbot.
Six experimental diets were designed to contain incremental amounts of crude protein (CP) ranging from 35 to 60% of the diet . sub-adult burbot were randomly distributed into 6 groups with four replicates and stocked into twenty-four 60 -L tanks (11 fish tank-1) in a closed recirculating system. Fish were fed the experimental diets to apparent satiation twice daily for 10 weeks. At the end of the experiment, fish in each tank were bulk weighed and sampled for fish fillet proximate and amino acids compositions, organosomatic indexes , physiological parameters in liver and tissue samples for gene expression for growth related parameters. Feed intake of each tank was measured on daily basis.
G rowth performance was significantly affected by dietary treatment, and the highest weight gain percentage was observed for fish fed diet with 50% protein and lowest was observed in diet with 35% protein (Figure 1), whereas feed conversion ratio (FCR) exhibited opposite trend. Feed intake data was positively correlated with growth performance. Condition factor, viscerosomatic index , h epatosomatic index and fillet yield were not significantly different among groups.
Using second-order polynomial regression analysis, the protein requirement for optimizing growth and feed efficiency was determined to 50% crude protein for burbot Lota lota maculosa . Data for the chemical composition of the fish fillets, physiological parameters and gene expression will be presented in the conference .
Conclusively, optimum dietary protein requirement of burbot is 50%.