Effects of dietary supplementation of synbiotic on growth performance, serum biochemical parameters and carcass composition in rainbow trout (Oncorhynchus mykiss) fingerlings.

The aim of this study was to evaluate the influence of a synbiotic (Biomin IMBO) on serum parameters and feeding efficiency in rainbow trout (Oncorhynchus mykiss) fingerlings. The fish with initial average weight of 4.59 ± 0.2 g were randomly assigned to four dietary treatments for two months. The dietary treatment (0.5, 1 and 1.5 g/kg of diet) was supplemented with basal diet and non-supplemented basal diet was used as control. After two months, all treatments supplemented with synbiotic showed significant (p < 0.05) increase in final mean weight, weight gain percentage, specific growth rate, condition factor, food conversion efficiency and survival rate, compared to the control group. Among all supplemented treatments, the best result in terms of growth factors and survival was observed in the treatment supplemented with 1 g synbiotic per kilogram of diet. Furthermore, supplementation with symbiotic, specifically 1 and 1.5 g/kg, significantly (p < 0.05) increased the total serum protein, but there was no significant (p > 0.05) difference in globulin content, albumin/globulin ratio, and triglyceride content among experimental treatments. In terms of body composition, carcass protein content of fish fed with synbiotic significantly (p < 0.05) increased compared to the control. These results revealed that a feeding regime with synbiotic for two months led to a significant increase in growth performance, survival rate and feeding efficiency in rainbow trout fingerlings.