The effect of fish protein digestion on the development of cod larvae / The effect of fish protein hydrolyzate on the development of cod larvae
One of the main problems with cod farming is severe declines in the early stages of maturation and the quality of juveniles. The aim of this project was to obtain a more complete picture of the effect of enrichment of food animals with saithe protein digestion on biochemical processes in early maturing cod by applying imaging methods and protein quantity analysis. The results indicate considerable antioxidant activity of saithe protein digestion as well as some effect on inflammatory activity. The performance of larvae in breeding experiments was rather low, although the growth rate was quite acceptable and there were few serious appearance defects. Treatment with saithe protein digestion did not appear to affect larval performance or defects, but there was evidence of stimulation of IgM and lysozyme production in the gastrointestinal tract and on the larval surface. Protein set analyzes showed that treatment affected the expression of cytoplasmic proteins, stress-involved proteins as well as the metabolic enzyme ATP-synthase. The results indicate that the use of saithe protein digestion can improve and even out the quality of juveniles if the quality of the eggs is deficient, but when good eggs are used, the treatment has no effect.
High larval mortalities and anatomical deformities are among the major obstacles restricting the development of Atlantic cod aquaculture. The present project was aimed at studying the effects of a pollock hydrolyzate supplementation during early developmental stages of cod on growth, development and survival. Furthermore, protein expression was evaluated as well as the distribution and intensities of selected parameters of the unspecific immune system. The hydrolyzate was found to display antioxidant activity and can be regarded as a feed supplement to the live prey items. The survival from larvae to juvenile in the experiment was relatively poor, with satisfactory larval growth and low incidence of severe deformities. Offering hydrlysate enhanced live prey to larvae did not affect larval survival or development. Treatment resulted in stimulated IgM and lysozyme production. Proteome analysis showed that treatment with fish hydrolysates has an effect on the expression of structural, stress and metabolic proteins. Overall, the results indicate that fortification of the live prey with pollock hydrolyzate can result in improved or more even larval quality following poor egg quality, however, with no effects if eggs are of better quality.