Effects of dietary rainbow trout (Oncorhynchus mykiss) visceral protein hydrolysate on growth performance, carcass composition, digestive enzymes, and bacterial flora of juvenile Siberian Sturgeon (Acipenser baerii)

This study was aimed to determine the effect of different levels of dietary rainbow trout (Oncorhynchus mykiss) visceral protein hydrolysate on growth performance, carcass composition, digestive enzymes, and bacterial flora of juvenile Siberian Sturgeon (Acipenser baerii). For this purpose, 300 juvenile Siberian Sturgeon with an average initail weight of 67±3 g were distributed in 12 tanks with a volume of 2000 L. 25 fish was introduced in each tank and were fed with different levels of protein hydrolysate (PH) in 4 treatments including 0 (control), 5 (5PH), 10 (10PH) and 20 (20PH) g of protein hydrolysate per kg of feed for 56 days. Based on the results, all growth indices improved in all treatments containing PH compared to the control (p<0.05) and the highest specific growth rate, weight gain and weight gain percentage were in 10PH and showed a significant difference compared to others (p<0.05). In this study, the lowest rate of feed conversion ratio was observed in 10PH and the highest rate was observed in the control. Fish fed with 10PH had also the highest amount of crude protein (19.10±0.14%) and the lowest percentage of lipid (5.60±0.15%). The results showed that the amylase and lipase enzyme activitites in 10PH treatment was significantly higher than other treatments (p<0.05). Also, trypsin enzyme activity in 10PH was significantly higher than the control and 5PH (p<0.05). The number of lactic acid bacteria in the treatment 10PH showed the highest numbers (p<0.05). In general, the effect of visceral protein hydrolysate, especially in treatment 10PH, on the growth indices, body composition, digestive enzymes, and the number of intestinal lactic acid bacteria of juvenile Siberian Sturgeon was positively and significantly evaluated and this treatment is recommended to improve the investigated parameters.