Effects of dietary chitosan oligosaccharides and Bacillus coagulans on the growth, innate immunity and resistance of koi (Cyprinus carpio koi)

The effects of oral administration of chitosan oligosaccharides (COS) and Bacillus coagulans, single or combined, on the growth performance, immunity and disease resistance of Cyprinus carpio koi were investigated. The koi (24.9 ± 0.52 g) were divided into 4 groups and each group was fed with diets supplemented with or without immunostimulant for 8 weeks. After 8 weeks of feeding trial, five koi per tank were sampled for immunity determination, ten koi per tank were challenged by Aeromonas veronii. The results showed that the koi fed with diets supplemented with a combination of the COS and B. coagulans had the highest final weight, specific growth rate (SGR), total leukocyte count (WBC), respiratory burst activity, phagocytic activity, lysozyme activity, SOD activity of koi and disease resistance to A. veronii (P < 0.05), followed by groups fed with diets with B. coagulans and COS, and the lowest in koi fed with the control diet. However, there were no significant differences (P < 0.05) in these growth index and immune parameters of koi and resistance to A. veronii between dietary B. coagulans and dietary COS. Under the experimental conditions, dietary B. coagulans and COS had a synergistic effect on enhancing immunity and disease resistance of koi (P < 0.05).

► We investigate the efficacy of COS and B. coagulans on koi.
► The COS and B. coagulans could enhance the growth and the immune responses.
► The COS and B. coagulans had a synergistic effect on enhancing immunity of koi.
► No differences in growth and the immune responses between COS and B. coagulans.