An experiment was conducted for 12 weeks to determine the effect of feeding and starvation on the survival and growth, the phenotypic trait and hepatosomatic index (HSI), the morphometric changes in the external and sectioned body, the biochemical changes, the hematological parameter, and respiration in olive flounder, Paralichthys olivaceus (Temminck et Schlegel).
The survival and growth of the starved group was lower than those of the fed group during the experiment. Starvation resulted in retardation of growth, which provides examples of the reduction of final body weight, growth rate of body weight, specific growth rate and condition factor, whereas the fed group continued to grow and remained in good condition. The starved group had lower gutted body weight, and similar viscera index and dressing percentage compared to those of the fed group. Although the starved group showed higher concentrations of protein and DNA than the fed group, food deprivation resulted in a decrease in the HSI. At the end of the experimental, the fed group (RNA/DNA=9.7) were significantly distinguished from the starved group (RNA/DNA=3.5)(P＜00.5).
The starved group resulted in a decrease in most sectioned body traits as well as condition factor and viscera index. In sectioned body traits, an almost the entire trunk region were significantly affected by feeding or starvation (P＜0.05). There was an increase in truss dimension of the body depth in trunk region of the fed group at the end of 12-week experiment. The value of trunk region dimensions with a large component of body depth in olive flounder is most likely to be compromised by variability related to differences in feeding regimes of fish in different habitats. Classical dimension of longitudinal length characteristics at body belly region increased when fed, and classical dimension of head characteristics increased when starved, but decreased when fed.
Blood analysis (hematocrit, hemoglobin, red blood cell, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration and mean corpuscular volume) showed no significant differences between the fed and starved groups at the end of the experiment (P＞0.05). There were no significant differences in plasma cortisol, glucose, Na+, Cl-, K+ and aspartate aminotransferase between the fed and starved groups (P＞0.05). Plasma alanine aminotransferase levels of the starved groups were higher than those of the fed groups, whereas plasma osmolality levels of the starved groups were lower than those of the fed groups. The results that oxygen consumption rate and respiration frequency of the starved group were lower than those of the fed group appeared that energy metabolism activity becomes low in the starved group.
These results suggest that all nutritional parameters used for starvation and feeding in this study appear to be a useful index of nutritional status in olive flounder. Additionally, the data have been interpreted in detail and some biologically important relationships were discussed.