Abstract
Different levels of mannan oligosaccharides (MOs) (100, 300 and 500 mg kg-1) were incorporated into a basal diet to formulate three diets, which were used to test the growth performance and innate immunity of loaches. The basal diet without any MOs served as the control. Loaches fed with MO-containing diets for 70 days showed a higher specific growth rate, condition factor, survival rate, intestine weight index, intestine length index, intestine Lactobacillus population, intestine Bifidobacterium population, phenoloxidase activity, superoxide dismutase activity, glutathione peroxidase activity, acid phosphatase activity, alkaline phosphatase activity, lysozyme level, complement 3 and resistance to Aeromonas hydrophila than the loaches in the control group. The feed conversion ratio, intestine Escherichia coli population, malondialdehyde level, aspartate aminotransferase level and alanine aminotransferase level showed an opposite trend. The optimal dose of dietary MOs required for the maximum growth of loaches was 300 mg kg-1. Results indicated that dietary MOs promoted the growth performance and innate immunity of loaches and could be used as a dietary supplement for loaches.