Dietary vitamin C requirement of juvenile Chinese sucker (Myxocyprinus asiaticus)

Abstract

An 8-week growth experiment was conducted to quantify the appropriate dietary vitamin C requirement of juvenile Chinese sucker (Myxocyprinus asiaticus). Triplicate groups of 30 experimental fish [initial body weight: (7.1 ± 0.3) g] were cultured in 500 L aquaria and fed with semi-purified diets containing six levels [10.1 (unsupplemented diet), 37.4, 64.9, 125.2, 244.2 and 482.0 mg kg−1 diet, respectively] of vitamin C (supplied as L-ascorbyl-2-polyphosphate). Results showed that weight gain of Chinese sucker was significantly increased with increasing dietary vitamin C levels, but there was no significant difference of weight gain among fish fed the diets containing more than 125.2 mg kg−1 vitamin C. As dietary vitamin C increased, the liver vitamin C content of fish showed the increasing trend firstly and then stabled, while the muscle vitamin C content significantly increased without reaching a constant level. Lower liver malondialdehyde content was observed in 125.2, 244.2 and 482.0 mg kg−1 vitamin C groups, and higher antioxidant capacity and superoxide dismutase activities were observed in supplemented groups when compared to the unsupplemented group. Liver aspartate aminotransferase and alkaline phosphatase activities were also significant affected by dietary vitamin C. Ash content of fish fed the diet with 244.2 or 482.0 mg kg−1 vitamin C was significantly higher than that of fish fed the other diets. However, dietary vitamin C had no significant effects on whole-body crude protein, lipid and moisture contents. The vitamin C requirement of juvenile Chinese sucker was estimated to be 84.6 and 126.1 mg kg−1 based on weight gain and liver vitamin C concentration respectively.