| Popis: |
In order to determine the minimal dietary zinc (Zn) requirements in the Chinese mitten crab, Eriocheir sinensis, we assessed the influence of dietary Zn levels on the weight gain, survival, fatty acid composition, expressions of fatty acid-binding protein (FABP) and metallothionein-1 (MT-1) transcripts at end of an 8-week feeding regime. Supplemental Zn (0, 10, 20, 40 and 80 mg kg−1 diet) was administered orally to crabs via the diet. The results indicate that dietary supplementation of 20 mg Zn kg−1 diet yielded the largest weight gain. While the hepatopancreatic concentrations of Zn increased progressively with the supplemental dosage, the hepatopancreas fatty acid composition was variable and dependent on supplementation. As the dietary Zn concentrations increased, 18:0 in crab hepatopancreas exhibited a downward trend, whereas 18:1 n-9, 18:3 n-3, 20:4 n-6 ( arachidonic acid,ARA) and 22:6 n-3 (docosahexaenoic acid, DHA) compositions exhibited a bell-curve response. The expressions of FABP and MT-1 transcripts were the highest in crabs receiving 20 or 40 mg Zn kg−1 diet corresponding to quantified levels of 27 or 44 mg Zn kg−1 diet. Taken together, these results suggest that dietary Zn deficiency may influence the synthesis and metabolism of fatty acids in the hepatopancreas of the mitten crab, an important aquaculture species. |
