Growth, digestive capacity and intestinal microflora of juvenile Jian carp (Cyprinus carpio var. Jian) fed graded levels of dietary inositol

A 60-day feeding trial was carried out with juvenile Jian carp (Cyprinus carpio var. Jian) to study the effects of myo-inositol (MI) on the growth, digestive enzyme and intestinal microbial population. Diets with seven levels of inositol (163.5, 232.7, 384.2, 535.8, 687.3, 838.8 and 990.3 mg MI kg(-1) diet) were fed to Jian carp (initial weight 22.28 +/- 0.07 g). Per cent weight gain (PWG) was improved with increasing inositol levels up to 535.8 mg MI kg(-1) diet (P < 0.05), and plateaued (P > 0.05). The protein production value, lipid production value and ash production value were increased with increasing dietary inositol levels up to 384.2, 838.8 and 838.8 mg MI kg(-1) diet respectively (P < 0.05). Although intestinal protein content and trypsin activity were not affected by inositol levels (P > 0.05), chymotrypsin, lipase and amylase activities in intestine were the lowest for fish fed the MI-unsupplemented diet (P < 0.05). Alkaline phosphatase, Na+, K+-ATPase, gamma-glutamyl transpeptidase and creatinkinase activities in the intestine were increased with an increase in the inositol levels up to 384.2-687.3 mg MI kg(-1) diet (P < 0.05). Intestinal Aeromonas hydrophila and Escherichia coli decreased with an increase in the levels of dietary inositol up to 232.7 and 687.3 mg MI kg(-1) diet respectively (P < 0.05), while Lactobacillus in the intestine increased with an increase in inositol levels up to 990.3 mg MI kg(-1) diet (P < 0.05). In conclusion, inositol improved growth, digestive capacity and intestinal microbial population of juvenile Jian carp, and the dietary inositol requirement for PWG of juvenile Jian carp is 518.0 mg MI kg(-1) diet.