Dietary choline requirement of juvenile narrow-clawed crayfish (Astacus leptodactylus) in a recirculating aquaculture system

It has been shown a dietary choline is essential for several crustacean species. However, the choline requirement of narrow-clawed crayfish has not been reported. Therefore, a 12-week feeding trial was conducted to determine the dietary choline requirement of narrow-clawed crayfish. Juvenile crayfish with an average body weight of 13.8±0.9g were intensively stocked in an indoor recirculating aquaculture system consisting of 12 tanks. Four experimental diets were formulated to contain graded levels of dietary choline (0, 0.2, 0.4 and 0.8% choline chloride). Results showed a crayfish fed diet with 0.0 and 0.2 % choline produced the highest and the lowest growth indices and enzymes activity including protease and amylase, respectively (P<0.05). With an increase of choline content of experimental diets (0.4 and 0.8 %), no significant improvement was observed regarding growth indices, protease, and amylase activity (P>0.05). However, no significant differences were observed in survival rate and lipase activity of various experimental groups (P>0.05). In conclusion, the results indicated that dietary inclusion of 0.2% choline would improve growth performance and digestive enzymes activity of juvenile narrow-clawed crayfish reared under intensive condition.