Dietary phosphatidylcholine requirements of red swamp crayfish (Procambarus clarkii)

To investigate the dietary phosphatidylcholine (PC) requirements of red swamp crayfish (Procambarus clarkii), crayfish (initial body weight, 9.92 ± 0.32 g) were hand-fed six diets containing 0.6 (control group, PC1), 5.6 (PC2), 10.7 (PC3), 15.9 (PC4), 20.8 (PC5), and 26.2 (PC6) g/kg, respectively, for 8 weeks. Supplemental PC from 5.6 to 15.9 g/kg significantly improved survival (P < 0.05). The weight gain rate and specific growth rate of PC4 group were significantly higher than that of PC1 group (P < 0.05). The minimum value of feed conversion ratio was observed in crayfish fed with PC3 diet (P < 0.05). The maximum value of crude fat content of muscle was found in group PC4 (P < 0.05). The lipase activity in intestine and hepatopancreas and the activities of catalase and superoxide dismutase in hepatopancreas first increased and then decreased, which was highest in group PC4 (P < 0.05). The activities of aspartate aminotransferase and alanine aminotransferase in serum and malondialdehyde content in hepatopancreas first decreased and then increased, with the minimum values in group PC3 and group PC1, respectively. Total cholesterol content in hemolymph, hepatopancreas, and muscle increased significantly in groups PC4, PC3, and PC2, respectively, compared with group PC1 (P < 0.05). Free fatty acid content in muscle increased by 22.73% in group PC5 compared with group PC1 (P < 0.05). According to the regression analysis, the dietary phosphatidylcholine requirements for red swamp crayfish were 13.05~15.25 g/kg.