Amino acid nutrition and metabolism
New findings were generated that in the long term may contribute towards formulation of improved diets for farmed fish. Background and objectives: The post-doctoral research stay was hosted by The Ohio State University, and supervised by Dr. Konrad Dabrowski. The principal objectives were to 1) test if the molecular form of dietary arginine affects growth and metabolism in bony fishes, 2) study if the expression of the urea cycle enzymes in fish early life stages affects arginine requirement, and 3) investigate if dietary antioxidants influence amino acid metabolism in fish. Results Dipeptide arginine is utilized just as well as free arginine in the freshwater fish species pacu. To determine amino acid requirements in fish, it is vital to supply the amino acids in an optimal molecular form, that is able to generate the highest growth rate and survival. In such studies, amino acids in the free form are usually added as supplements in a graded fashion to the experimental diets. However, it was not known if dipeptides can be used as supplements in such diets for adult fish. We studied how a dipeptide supplement, containing arginine, compared to the growth performance of fish fed arginine in the free form. The South American fish pacu was studied, which is gaining interest as an aquaculture species in the region. The results showed that arginine supplied in the dipeptide form was able to sustain growth and feed efficiency at a level comparable to diets containing arginine in the free form. In future studies, it would be interesting to test how other fish species, like salmon and trout, perform when fed dipeptide supplemented diets.
