| Eff ects of irradiated and non-irradiated Ergosan extract (alginic acid) on rainbow trout growth
performance and skin mucosal immunity were compared. Ergosan was irradiated at 30 kGy in a cobalt-60
irradiator. A total of 252 fi sh (128.03±9.4 g) were randomly divided into four equal groups, given the basal
diet either unsupplemented with Ergosan (control group) or supplemented with crude Ergosan (5 g/kg),
ethanol-extracted Ergosan (0.33 g/kg) or irradiated Ergosan (0.33 g/kg) according to this protocol: basal diet
for 15 days, treatment diet for 15 days, basal diet for 10 days and treatment diet for 15 days. Highest growth
performance was observed in fi sh fed irradiated Ergosan ( P <0.05). Dietary administration of diff erent
Ergosan types did not cause any changes in mucus protein level, but improved alkaline phosphatase level
and hemagglutination titer compared with the control (basal diet without Ergosan) on day 55 of feeding trial
( P <0.05). Furthermore, the highest value of lysozyme activity was observed in gamma-irradiated Ergosan
on day 55. In conclusion, gamma-irradiated Ergosan at 0.33 g/kg was found to improve growth performance
and mucus biological components signifi cantly in comparison with the control group (basal diet without
Ergosan). |