Effect of dietary nucleotides on some growth performance and apparent digestibility of Sterlet sturgeon (Acipenser ruthenus Linnaeus, 1758)

The present study was performed to investigate the effect of dietary nucleotides on the growth and apparent digestibility of Sterlet sturgeon, Acipenser ruthenus. Fish with an average body weight of 95.33±1.23g and total length of 0.30±0.5 cm were divided into 5 experimental groups with 3 replications, each containing 12 fish which were randomly distributed in tanks with 500 L working capacity. The fish were fed diets containing 0.0, 1.5, 2.5, 3.5, and 5.0 g kg-1 nucleotide. The experiment was conducted in a completely random design for 10 weeks. The results showed a significant increase in the weight gain percentage of fish in treatments of 2.5, 3.5, and 5.0 g kg-1 nucleotide than those in the control treatment (P<0.05), reaching the highest percentage of 119.07±19.97% in fish fed diet supplemented with 5.0 g kg-1 nucleotide (P<0.05). However, no significant difference was recorded in the values of this variable between fish-fed diets supplemented with more than 2.5 g kg-1 nucleotide (P>0.05). There was also a significant increase in the total length of fish fed diet supplemented with 5.0 g kg-1 nucleotide (25.5±0.8 %) compared to those fed the basal diet (17.76±0.73 %) (P<0.05), while no significant difference was found with those in fish fed diet supplemented with 3.5 g kg-1 nucleotide (P>0.05). The highest apparent digestibility of dry weight was 80.32±0.47% in fish fed a diet containing 5.0 g kg-1 nucleotide, while the lowest value was 73.24±0.45% in fish fed the basal diet (P<0.05). The highest apparent digestibility of protein was 90.94±0.24% in fish-fed a diet containing 5.0 g kg-1 nucleotide, which had a significant difference with that in fish fed a diet containing less than 2.5 g kg-1 nucleotide (P<0.05). However, no significant difference was observed in lipid apparent digestibility of fish between the experimental treatments (P>0.05). In general, findings of the present research indicated that dietary supplementation of nucleotide in the diet has a significant impact on the nutrient digestibility of sterlet sturgeon, with the best response obtained when fish fed a diet containing 3.5 g kg-1 nucleotide for ten weeks.