INFLUENCE OF DIETARY GLUCAN AND VITAMIN-C ON NONSPECIFIC AND SPECIFICIMMUNE-RESPONSES OF RAINBOW-TROUT (ONCORHYNCHUS-MYKISS)

A trial was conducted to determine the effect of a combination of diet ary glucan and vitamin C on the immune response of rainbow trout. Afte r 3 weeks of adaptation on a control diet (without glucan but containi ng 150 ppm vitamin C), rainbow trout were fed the experimental diets c ontaining yeast glucan and vitamin C at 150, 1000 and 4000 ppm for 2 w eeks and then switched back to the control diet for the following 4 we eks. Macrophage activity (chemiluminescence response), complement acti vation and lysozyme levels were monitored just after feeding the exper imental diets (week 0) and 2 and 4 weeks later. The kinetics of antibo dy response after vaccination against enteric redmouth disease were de termined. The fish were immunised at week 0, at the end of the experim ental feeding. Tissue ascorbic acid contents were monitored every 2 we eks and reflected the dietary treatments. No differences were observed in complement levels activated via the classical pathway, Two weeks a fter feeding the experimental diets, alternative pathway of complement activation and chemiluminescence response were enhanced by high doses of vitamin C. Significant enhancement of macrophage activity was stil l evident at week 2. No significant differences were observed in lysoz yme levels. The specific immune antibody response was enhanced followi ng vaccination, when glucan was also present in the diet.