Dietary chitosan oligosaccharides modulate the growth, intestine digestive enzymes, body composition and nonspecific immunity of loach Paramisgurnus dabryanus

Abstract Three test diets containing three different levels (1, 3, and 5 g kg −1 ) of dietary chitosan oligosaccharides (COs) were formulated and used to test the growth performance, body composition, intestine digestive enzymes, antioxidant responses and resistance to Aeromonas hydrophila of loach Paramisgurnus dabryanus . A basal diet without any COs served as the control. After 60 days of feeding, the growth performance, intestine digestive-enzyme activities, body protein content and total polyunsaturated fatty acids, antioxidant responses, and resistance to A. hydrophila of loach P. dabryanus were higher than those of the control when the loach P. dabryanus was fed with CO-containing diets. The optimum dose of dietary COs required for the maximum growth of loach was 3 g kg −1 of the diet. Results indicated that dietary COs can improve the growth performance, body composition, intestine digestive enzymes, antioxidant responses, and resistance to A. hydrophila of loach P. dabryanus and can thus be used as a diet supplement for them.