This study evaluates the effect of dietary supplementation of
immunostimulants on the Chinese mitten crab (Eriocheir sinensis) with a single administration of
mannan oligosaccharide (MOS), or its combination with either β-
glucan or with
inulin for 8 weeks. Four diets included an untreated control diet (C), MOS alone (3 g kg-1, M), MOS with β-
glucan (3 g kg -1 MOS + 1.5 g kg -1 β-
glucan, MB), and MOS with
inulin (3 g kg -1 MOS + 10 g kg -1
inulin, MI). The
weight gain and specific growth rate of the crabs fed M, MB, and MI diets were improved by lowing feed conversion ratio. The growth and feed utilization of the crabs fed the MB diet were improved compared with the other three groups. The crabs fed the M, MB and MI diets showed a higher intestinal
trypsin activity than that in the M and control groups. The highest
trypsin activity in the hepatopancreas was observed in the MB group. Crabs fed M, MB and MI diets increased
antioxidant system-related
enzyme activities, but reduced
malondialdehyde. The highest activities of
alkaline phosphatase,
acid phosphatase,
lysozyme and
phenol oxidase in the gut and the respiratory burst of the crabs were found in the MB group. The MB diet promoted the
mRNA expression of E. sinensis immune genes (ES-PT, ES-Relish, ES-LITAF, p38MAPK and
Crustin) compared with the control. After 3 days of
infection with Aeromonas hydrophila, the highest survival of crabs was also found in the MB group. This study indicates that the combination of MOS with β-
glucan or with
inulin can improve growth,
antioxidant capacity, non-specific immunity and
disease resistance in E. sinensis.