Effects of various feeding and starvation strategies on growth, hematological and biochemical parameters, and body composition of Caspian brown trout (Salmo caspius Kessler 1877) parr

This study was carried out to investigate the effects of starvation and feeding regimes on growth performance, haematological and biochemical parameters of blood and body composition of Caspian brown trout parr. For this purpose, 900 fish (average weight: 12.5±1 g) were stocked in 300-l tanks (18 tanks at a stocking rate of 50 fish in each tank) using an open system. Six experimental groups composed of feeding and starvation regimes were considered for the experiment as follows: FFF (Six weeks feeding), SSS (Six weeks starvation), SFS (Two weeks starvation + two weeks feeding + two weeks starvation), FSF (Two weeks feeding + two weeks starvation + two weeks feeding), FS (Three weeks feeding+three weeks starvation), and SF (Three weeks starvation + three weeks feeding). According to results obtained, the growth rate (GR), special growth rate (SGR), condition factor (K) and hepatosomatic index (HSI) decreased as the length of starvation periods increased (p<0.05). The haemoglobin content and haematocrit did not seem to be affected by starvation (p>0.05) while the highest values of red blood cells (RBCs) and white blood cells (WBCs) were observed in the SSS group (p<0.05). Also, the lower values of MCH (haemoglobin concentration in one RBC) and MCV (mean volume of one RBC) were observed in the SSS group (p<0.05). The lipid content of body tissue decreased with increased length of the starvation period (p<0.05), wherase the total protein, ash and moisture showed no differences between the experimental groups (p>0.05). In conclusion, our results showed that starvation has significant physiological and morphological effects on Caspian brown trout parr.