Effects of dietary starch levels on the growth, plasma metabolites and expression of genes involved in glucose transport and metabolism inPelodiscus sinensisjuveniles

Abstract

Listen

Translate article

A 10-week feeding trial was conducted to evaluate the growth performance, glucose transport and metabolism of Chinese soft-shelled turtles (Pelodiscus sinensis) exposure to graded levels of dietary starch (0.52%, 7.43%, 14.74%, 22.99% and 31.38%). The 360 turtles (initial body weight, 12.94 ± 0.50 g) with 12 replicates were randomly assigned to five experimental diets. The highest weight gain and specific growth rate (SGR) were observed in 7.43% group and the lowest in 31.38% group. The protein efficiency ratio, whole-body lipid contents, hepatic glycogen contents and the 4-hr postprandial plasma glucose levels were significantly increased with the increment of starch levels (p < .05). In contrast, the daily feed intake and feed conversion ration were significantly declined (p < .05). The mRNA levels of glucose transporter 2, glucokinase, pyruvate kinase, malic enzyme and acetyl-CoA carboxylase alpha genes in the liver significantly increased as the increase in starch levels at 4-hr and 24-hr post feeding (p < .05). No significant differences were observed in the expression of gluconeogenesis genes at each time point (p > .05). These results suggested that dietary addition of starch up-regulated hepatic glycolysis, glycogenesis and lipogenesis genes expression, but the deficient response of gluconeogenesis to dietary starch might be part of the causes limited the starch utilization. Based on the secondary polynomial regression of SGR, y = −0.0011x2 + 0.028x + 1.63 (R2 = 0.9292), the 12.73% inclusion level of dietary starch was recommended in juvenile turtles.