Optimal dietary L ‐ascorbyl‐2‐monophosphate inclusion improved the growth performance and nonspecific immunity of red swamp crayfish ( Procambarus clarkii )

Abstract

L-ascorbyl-2-monophosphate (AMP) was used as a vitamin C source to investigate its effects on growth performance and nonspecific immunity of red swamp crayfish (Procambarus clarkii). Six experimental diets (AMP0, AMP15, AMP30, AMP45, AMP60 and AMP75) with different levels of AMP (.00, 141.01, 280.44, 419.06, 558.13 and 692.09 mg kg−1 diet, respectively) were fed to juvenile crayfish (average weight: .70 ± .01 g) for 56 days. At the end of the 56-day trial, the highest final body weight, specific growth rate (SGR), phenoloxidase activity, lysozyme activity, superoxide dismutase activity and anti-superoxide anion activity all occurred in the AMP30 group (p < .05). Compared with the AMP0 group, crayfish fed with AMP-supplemented diets showed significantly higher hepatosomatic index value (p < .05). Conversely, the feed conversion ratio value of crayfish fed with AMP-supplemented diets was significantly reduced relative to that of the AMP0 group (p < .05). AMP15 to AMP30 diets showed significantly higher muscle rate value, crude protein content, total haemocyte count and blood cell respiratory burst activity (p < .05). Broken-line regression analysis on SGR indicated that the optimal dietary AMP level of red swamp crayfish was estimated to be 300.95 mg kg−1 diet.