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Effects of dietary folic acid on growth, antioxidant capacity, non‐specific immune response and disease resistance of juvenile Chinese mitten crab Eriocheir sinensis (Milne‐Edwards, 1853)

Wei, J.J., Zhang, F., Tian, W.J., Kong, Y.Q., Li, Q., Yu, N., Du, Z.Y., Wu, Q.Q., Qin, J.G., Chen, L.Q.
Aquaculture nutrition 2016 v.22 no.3 pp. 567-574
Aeromonas hydrophila, Eriocheir sinensis, acid phosphatase, alkaline phosphatase, antioxidant activity, crabs, diet, disease resistance, feed conversion, folic acid, glutathione transferase, hemocytes, immune response, juveniles, lysozyme, malondialdehyde, monophenol monooxygenase, mortality, oxygen, pH, pathogens, superoxide dismutase, tanks, vitamin B12
An 8‐week study was conducted to determine folic acid requirement and its effect on antioxidant capacity and immunity in juvenile Chinese mitten crab Eriocheir sinensis (Milne‐Edwards, 1853), followed by a challenge assay with the pathogen Aeromonas hydrophila for 2 weeks. Folic acid was added to a basal diet at seven levels (0, 0.5, 1.0, 2.0, 4.0, 8.0, 16.0 mg folic acid kg⁻¹ diet), and a diet free of folic acid and vitamin B₁₂ was also included as a control. Crabs were fed twice daily in 32 tanks with 7.76–8.17 mg oxygen L⁻¹, 25.0–31.0 °C and 7.5–8.3 pH. Growth and feed efficiency were significantly greater in crabs fed ≥2.0 mg folic acid kg⁻¹, but not significantly different between crabs fed diets >2.0 mg folic acid. The superoxide dismutase activity and glutathione S‐transferase activity were highest in crabs fed ≥2.0 mg folic acid kg⁻¹, followed by those fed 0.5 and 1.0 mg folic acid kg⁻¹, and the control diet. The malondialdehyde content was highest in crabs fed the control diet, followed by those fed 0 mg folic acid kg⁻¹, and the lowest value occurred in those fed ≥0.5 mg folic acid kg⁻¹. Phenoloxidase activity and total haemocytes were significantly higher in crabs fed ≥2.0 mg folic acid kg⁻¹ than other diets. Crabs fed 2.0 mg folic acid kg⁻¹ had the highest lysozyme, acid phosphatase and alkaline phosphatase activities but the lowest cumulative mortality. The optimum dietary folic acid requirement by E. sinensis was estimated at 2.29–2.90 mg kg⁻¹ diet.