Dietary phosphorus affects growth, glucolipid metabolism, antioxidant activity and immune status of juvenile blunt snout bream (Megalobrama amblycephala)

Abstract

A 10-week feeding trial was conducted to investigate the effects of dietary phosphorus on the growth, glucolipid metabolism, antioxidant activity and immune status of the juvenile blunt snout bream. The fish were fed with three experimental diets containing graded phosphorus levels ranging from 8.1 (P8.1), 11.5 (P11.5) and 14.3 (P14.3) g/kg diet. The growth performance was significantly improved with increasing dietary phosphorus levels. Whole body ash content was highest in fish fed the P14.3 diet, while the lipid content showed the reverse trend. Plasma phosphorus, calcium and total protein contents increased significantly with increasing dietary phosphorus levels, and the lowest activities of alanine transaminase and content of triglycerides were observed in the P14.3 diet. The P11.5 diet enhanced glycolysis and lipid synthesis by improving the expression of core genes of glycometabolism and inhibiting the expression of key genes related to lipid synthesis. The P11.5 diet also improved the antioxidant capacity by activating the nuclear factor erythroid 2-related factor 2 signaling pathway and the activities of antioxidant enzymes. Besides, the expression of pro-inflammatory factor genes was reduced while the expression of anti-inflammatory factor genes was improved by dietary phosphorous supplementation. These results demonstrated that an appropriate phosphorus supplementation level has positive effects on growth, glucolipid metabolism, and health of the juvenile blunt snout bream.