Effects of dietary mannan oligosaccharide on the survival,growth, immunity and digestive enzyme activity of freshwater crayfish,Cherax destructor Clark (1936)

The aim of this experiment was to determine the effects of dietary supplementation of Bio‐Mos^® as a source of mannan oligosaccharide (MOS) on the growth, survival, immunity and digestive enzyme activity of freshwater crayfish, Cherax destructor (yabby). A basal diet and another diet with 0.4% of Bio‐Mos^® supplemented to the basal diet were formulated. Each diet was provided to eight yabbies (35.14 ± 0.48 g, initial weight) replicated 3 times in individual 250‐L plastic cylindrical tanks for a duration of 56 days. Each tank was provided with an independent recirculating water system filtered with a biological filtration. Growth parameters such as weight, specific growth rate and average weekly gain of Bio‐Mos^®‐fed yabbies were higher (P < 0.05) than yabbies fed the control diet. Total haemocyte count, granular cells and semi‐granular cells were also higher in the yabbies fed Bio‐Mos^® diet. Protease activity was higher in hepatopancreas, and amylase activity was higher in the guts of yabbies fed Bio‐Mos^® diet. The results implies that supplementation of MOS through Bio‐Mos^® can effectively improve growth and immunological condition of yabbies.