Effects of the dietary supplementation of manganese on growth, skeletal development, oxidative stress and bone metabolism related genes in gilthead seabream (Sparus aurata) larvae

Summary

Manganese (Mn) is an essential element necessary for normal growth, antioxidant defense and maintaining bone health. Knowledge about the effects of dietary Mn levels in gilthead seabream (Sparus aurata) larvae performance is still scarce. To determine the effects of dietary Mn levels on growth, survival, skeletal development and expression of antioxidant and bone metabolism related genes, gilthead seabream larvae were fed six experimental microdiets supplemented with manganese sulfate monohydrate (MnSO4.H2O) (contained 6.3, 39, 75, 79, 200 and 270 mg Mn/kg diet). After 26 days of feeding, dietary Mn levels had no effect on larval survival. However, larvae fed the non-supplemented diet (6.3 mg Mn/kg) showed signs of Mn deficiency, including growth reduction, low whole body Mn content, lower expression of mnsod, runx2, oc, and reduced bone mineralization. The poor vertebral body mineralization and low bone relative gene expression in seabream larvae was related to a marked increase in the number of fish with total skeletal anomalies and anomalies of the caudal vertebrae region. On the contrary, larvae fed with Mn supplemented diet up to 270 mg Mn/kg showed increased growth and whole body Mn content, up-regulated mnsod, runx2, alp, opn and oc expression, as well as increased bone mineralization, and reduced number of fish with skeletal anomalies. Therefore, the findings suggest that adequate dietary Mn supplementation positively influences the growth, skeletal development, and antioxidant defense of gilthead seabream larvae, preventing the manifestation of Mn deficiency-related issues.