Effect of dietary nucleotides on some growth parameters, carcass composition and some stress indices in Snow trout (Schizothorax zarudnyi)

Dietary nucleotide has been shown to improve growth indices, nutritional function and higher vertebrates in fish.
We investigated the effect of different levels of dietary nucleotide on growth parameters, whole-body composition and fluctuations of cortisol and glucose due to acute stress in Snow trout (Schizothorax zarudnyi).
One-hundred-twenty Snow trout fingerlings with average weight 7.58±0.05g, were fed with four levels of dietary nucleotides including 0 (control), 0.15, 0.25, and 0.5 percent for 8 weeks. Ten fingerlings were stocked into each 300l tank with triplicate in four treatments and fed three times daily at 3-5% body weight rate. At the end of feeding trial, weight gain, Weight gain rate, feed efficiency, Food efficiency ratio and survival were computed. Also, the numbers of fish that were exposed to acute stress (temperature and pH).
The results showed that none of the nucleotide-supplemented diets had any significant effect on growth indices (p>0.05). None of the dietary treatments resulted in any significant changes to dry matter, ash and protein. The only significant difference was observed in the fat (p>0.05). The fish fed 0.25% nucleotide showed higher whole lipid compared to other dietary treatments. Stress test results showed no significant difference at the beginning of the experiment, whereas after, acute stress cortisol levels were significantly higher in trials. The lowest response was observed in trial with 0.50% nucleotide and the highest was in control groups. Glucose levels were not significantly different, neither before nor after acute stress.
The nucleotide composition used in the present study failed to provide significant effects on growth of Snow trout juveniles but could improve response to acute stress.