Effects of graded levels of dietary vitamin C on the growth, digestive capacity and intestinal microflora of juvenile Jian carp ( Cyprinus carpio var. Jian).

A 60-day experiment was carried out to study the effects of vitamin C [ascorbic acid (AA)] on the growth, digestive enzyme activities and intestinal microbial population. Diets with six levels (0.0, 21.4, 45.1, 69.5, 93.6 and 142.1 mg AA kg diet) of supplemental ascorbyl polyphosphate were fed to juvenile Jian carp ( Cyprinus carpio var. Jian) (12.63±0.02 g). The specific growth rate (SGR), feed efficiency and productive protein value were significantly improved with increasing AA levels up to 45.1 mg AA kg diet ( P<0.05). The hepatopancreas and muscle AA concentrations were increased with increasing dietary AA levels up to 69.5 and 45.1 mg kg diet respectively ( P<0.05). The activities of intestinal trypsin, chymotrypsin, lipase, α-amylase, Na, K-ATPase, alkaline phosphatase, gamma-glutamyl transpeptidase and creatinkinase were all positively affected by the AA supplementation ( P<0.05). Intestinal Lactobacillus and Bacillus were increased with increasing AA levels up to 45.1 mg AA kg diet ( P<0.05), while intestinal Escherichia coli decreased with increasing AA levels up to 45.1 mg AA kg diet ( P<0.05). In conclusion, AA improve the digestive capacity and intestinal microbial population of Jian carp, and the dietary AA requirement for SGR of juvenile Jian carp was 40.9 mg AA kg diet. [ABSTRACT FROM AUTHOR]