Antioxidant and osteoinductive properties of organic selenium in microdiets for gilthead seabream (Sparus aurata) larvae

Abstract

This study investigated the effect of yeast derived selenium (Se) dietary supplementation on larval performance, whole body mineral contents, lipid peroxidation, fatty acid profiles, expression of antioxidants and bone biomarkers genes, mineralization and skeletal anomalies in gilthead seabream ( Sparus aurata ) larvae. Five experimental microdiets containing 1.4, 6.1, 9.2, 12.0 and 14.0 mg Se/kg diets were fed to triplicate groups of larvae (total length: 7.26 +/- 0.83 mm, 30 dph) for 21 days. Larval Se levels increased proportionally to the elevation of dietary Se. Those fed with dietary Se level at 6.1 mg/kg had a higher growth performance than those fed with non -supplemented diet (1.4 mg/kg), then reached a plateau from larvae fed with Se6.1 to Se14 diet although growth was not significantly affected by different diets. In addition, larval survival was not significantly affected. However, larvae fed the lowest Se levels showed a significant increase in lipid peroxidation, the downregulation of antioxidant genes, a reduction in polyunsaturated fatty acids (PUFA) contents and the highest incidence of skeletal anomalies. While increase up to 6.1 - 12 mg Se/kg, reduced oxidative stress, increased PUFA, vertebral mineralization, up -regulated antioxidant and bone metabolism related genes and contributing to reduce skeletal anomalies of larvae. However, further increase in dietary Se up to 14 mg/kg led to the lowest gpx, cat and alp expressions, in agreement with a lower mineralization. These findings suggest, dietary Se level at 6.1 mg/kg would be the minimum dietary Se level required in microdiets for gilthead seabream larvae. Thus, the study demonstrates the importance of dietary Se for bone metabolism and mineralization due to its antioxidant and osteo-inductive properties.