فهرست نشریات علمی دسترسی آزاد ایران

Fish in an optimum temperature range seem to have different nutritional requirements compared to optimal conditions. To evaluate the effect of different dietary protein levels during winter feeding of Beluga sturgeon, Huso huso (334.1 ± 0.3 g initial body weight; mean ± SD) a feeding trial with 8 weeks duration was conducted. Four diets with three replicates were formulated containing different dietary protein levels of 32%, 36%, 40% and 44% with 14.5% crude fat at low temperature of 8.8 ± 2.0 °C in twelve circular concrete tanks (900 L volume; 5 fish per tank). Fish were fed 1% of body weight three times daily, and at the end of the experiment, fish were weighed and sampled for plasma biochemical indices. The results have shown that various dietary protein levels had no noteworthy effect on growth indices (p > 0.05). The highest numerical, but not significant, final weight, specific growth rate, protein and lipid efficiency ratios were found in diets comprising 36% protein. No mortality was recorded throughout the trial. The results of biochemical plasma parameters showed that triglyceride, cholesterol, and total protein were not influenced by dietary protein levels (p > 0.05), while the glucose in fish fed 44% protein was significantly lower than the other treatments (p < 0.05). Hematocrit was significantly increased by increasing dietary protein levels, and the highest value was observed in the 44% treatment (p < 0.05). Based on the findings, it is advised that a protein level of 36% would be beneficial for optimal growth and physiological conditions in winter feeding of juvenile Beluga sturgeon.