Growth, survival and immune response of male freshwater prawn Cryphiops (Cryphiops) caementarius fed with crude chitin

Shellfish by-products (exoskeletons) possess nutrients and chitin that can be used to improve the growth and immunity response of cultured animals. To evaluate the effect of crude chitin in the growth, survival, and immune response of male freshwater prawn Cryphiops (Cryphiops) caementarius, we tested prawn diets supplemented with different amounts of chitin obtained from prawn exoskeletons. We used a control (basal) diet and three experimental diets supplemented with crude chitin: D15 (basal diet + 15% crude chitin), D20 (basal diet + 20% crude chitin), and D25 (basal diet + 25% crude chitin). After 60 days, the growth parameters and organosomatic indices were similar (P > 0.05) among treatments, but higher weight gain (31.88%), specific growth rate (0.433%/day), and organosomatic indices were obtained with the D25 diet, although survival rate for this diet was low (56%). Immune response analysis revealed that hemolymph clotting time was similar (P > 0.05) among dietary treatments. However, compared with the control diet, pure chitin in D20 and D25 diets (10.50% and 12.40%, respectively) accounted for the increase (P < 0.05) in total hemocytes (148.38 and 149.87 × 10⁵ cells/mL), granular hemocytes ( 95.38 and 97.69 × 10⁵ cells/mL), semigranular (33.56 and 42.38 × 10⁵ cells/mL), hyaline (19.38 and 9.50 × 10⁵ cells/mL), and the decrease in atypical hemocytes (0.07 and 0.31 × 10⁵ cells/mL). In conclusion, the crude chitin diets did not affect (P > 0.05) growth or survival, but the D20 and D25 diets caused a significant increase (P < 0.05) in circulating hemocytes, corroborating that chitin can stimulate immune response in prawns and thus it can be used to improve aquaculture productivity.