Growth and hematological changes of Aspikutum, a hybrid of Leuciscus aspius female (Linnaeus, 1758) × Rutilus frisii male (Kamensky, 1901), fed rations with various protein to lipid ratio

A 60-day trial with six diets (three different protein levels × two different lipid levels) containing 30, 35 and 40% protein with 10 and 15% lipid levels was conducted to determine the optimum dietary protein to lipid ratio and effects on growth performance and hematological indices of Aspikutum, Leuciscus aspius female×Rutilus frisii male. Two hundred and fifty two fish (31.2±0.4 g; mean±SEM) were distributed in 18 circular concrete tanks (400 L) and were fed 3 times daily according to their apparent satiation. The results showed that the highest growth rate was achieved when fish fed with diet containing 35% protein and 15% lipid. Lipid productive value was significantly decreased with increasing dietary lipid level. Number of red blood cells, white blood cells, hemoglobin concentration, hematocrit value, mean corpuscular volume, mean corpuscular hemoglobin, neutrophil and eosinophil were not considerably differing among rearing treatments, while mean corpuscular hemoglobin concentration was significantly higher in fish fed with diet containing 30% protein and 10% lipid. The percentage of lymphocyte increased with increasing dietary lipid level, whereas a decrease of monocyte percentage was observed with increasing of dietary lipid level. Dietary protein and lipid level, as well as the interaction showed no significant differences in total lipid, triglyceride, cholesterol and total protein levels. In general, this study has indicated that diet containing 35% protein and 15% lipid had positive effects on growth performance, while no effects on biochemical and hematological parameters was achieved.