The effects of starvation and refeeding on plasma amino acid levels in carp, Cyprinus carpio L., 1758

Abstract

Plasma amino acid (AA) levels of carp, Cyprinus carpio L., 1758, were analysed after various periods of starvation as well as after 12 days of refeeding. The levels were compared to control groups, which had been previously fasted for 24 h. A positive correlation between dietary and plasma essential amino acid (EAA) concentrations was observed in all of the control groups.The effect of starvation on the dynamics of AA concentration was different according to the period of starvation. Fasting already produced a decrease of total α‐AA levels at 2 days, and these low levels were maintained until 5 and 8 days. These short periods of fasting affected the levels of EAA (especially branched‐chain AA) more than those of non‐essential amino acids (NEAA). The only AA that increased was Ala, which rose at 5 days of starvation, surpassing the levels of the control group. These high levels were maintained until 19 days of starvation.A different situation was observed at 19 days, when an important increase of total α‐AA levels was produced, the branched‐chain AA being the most notable among EAA and Glu/Gln among NEAA. Later, at 50 days of starvation, total α‐AA, EAA (except Leu and Ile) and NEAA decreased.After 50 days of starvation, 12 days of refeeding did not modify the levels of EAA and NEAA, and their concentrations were lower than those of the control group, which presented an increase of total AA at this time. The differences observed on the changes of individual AA levels are discussed.