Influence of dietary protein/lipid ratio on growth performance and body composition of Aspikutum, a new hybrid of Leuciscus aspius ♀ × Rutilus frisii ♂ (Teleostei: Cyprinidae)

A 3×2 factorial experiment with six trial diets containing three protein levels (30, 35 and 40%) and two lipid levels (10 and 15%) was conducted to investigate the optimum dietary protein to lipid ratio of Aspikutum, Leuciscus aspius ♀ × Rutilus frisii ♂. In this experiment, 252 fish (31.22±0.38g; mean±SE) were stocked in 18 tanks with the volume of 400L and were fed 3 times daily for 60 days. The results indicated that growth performance and feed conversion ratio was significantly affected by protein content of the diet, so that these parameters increased significantly with increasing protein level from 30% to 35%, and then decreased in 40%. Protein efficiency ratio and hepatosomatic index decreased with increasing dietary protein level. Lipid efficiency ratio decreased with increasing dietary lipid level. Lipid content of carcass was decreased with increasing the dietary protein, so that the highest amount of lipid was observed in fish fed by 30% protein and 15% lipid. Also, body moisture of fish fed by 40% protein and 15% lipid was higher than those of other treatments. In general, the results indicated that diet containing 35% protein and 15% lipid is suitable for the optimum growth and feed utilization of Aspikutum in juvenile stage.