Prebiotic effect of fructo–oligosaccharides on growth and physiological state of rainbow trout, Oncorhynchus mykiss (Walbaum)

Rainbow trout at an average weight of 240 g were examined for the effect of dietary fructo–oligosaccharides in the diet on their growth and physiological state through selected biochemical parameters of the blood plasma. The prebiotic product Profeed® (experimental group, EG) was administered on a continuous basis at a rate of g kg−1 of pellets for 105 days. The best growth performance for the EG was found in 42 days (363 ± 34.7 g vs. 340 ± 36.7 g, P = 0.003) and in 63 days (387 ± 35.6 g vs. 364 ± 42.3 g, P = 0.011). SGR of the fish from the EG was 0.69% and from the control group (CG) was 0.70%. The feed conversion level was 0.82 in the EG and 0.86 in the CG. Survival rate was 99% (EG) and 98% (CG). The results of the biochemical examination indicate significant differences in the creatinine (28 ± 5.5 vs. 22 ± 3.05 µmol L−1) and the sodium cation (157.9 1.66 vs. 155.7 ± 1.49 mmol L−1) level and in the catalytic concentration of alkaline phosphatase (5.18 ± 1.57 vs. 3.43 ± 0.78 µkat L−1). The positive results of the growth and biochemical tests as well as the favourable feed conversion suggest that it would be worthwhile to test higher concentrations of the Profeed® prebiotic product