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Abstract
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The purpose of this study was to evaluate the effects of glucan on growth performance and immunity of the Rainbow trout. 360 specimens of the Rainbow trout fingerling with an average initial weight of 10±0.42 gr distributed into four treatments with three replicates and were fed with four diets including a control diet, vaccine, vaccine and glucan, and glucan in interval of 10 days for 6 weeks. At the end of the experiment, the average final weight, percent, weight gain and PER of fish fed diets containing glucan were significantly higher compared to the control treatment (p<0.05). However, there was significant difference compared to the group fed with vaccine and vaccine plus glucan (p>0.05). The best growth performance in terms of daily weight gain (with 0.293±0.05), percent weight gain (with 138.79±0.4) and protein efficiency ratio (with 2.4±0.04) were seen with glucan. Neutrophil levels of fish fed diets containing glucan plus vaccine were significantly higher compared to the control treatment (p<0.05). However, regarding the lymphocyte and monocyte, there was no significant difference in the treatments. The result of survival of fish challenged with Streptococcus iniae via bath route was 55%, while those for the vaccine treatment, macrogard plus vaccine, every 10 days interval was 75%, 86%, 60 and 55%, respectively. The results of this study showed that the dietary glucan had a significant impact on the growth performance and non-specific immune responses of the Rainbow trout.
Key words: Vaccine, Streptococcus, ?-glucan, Rainbow Trout
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