Effects of dietary zinc on growth, bone-related genes expression and skeletal anomalies in gilthead seabream (Sparus aurata) larvae

Abstract

Zinc (Zn) is one of the essential nutrients required for growth and bone development in all vertebrates. Zn deficiency has been related to demineralization of bones and low growth in fish. The present study was conducted to determine the role of dietary Zn levels on growth, bone mineralization, gene expression and skeletal anomalies during early developmental stages of gilthead seabream (Sparus aurata). For that purpose, larvae were fed with six microdiets containing different levels of Zn: 79, 98, 110, 130, 150, and 248 mg Zn/kg diets, respectively. After 16 days of feeding, larvae fed diets with110 and 130 mg Zn/kg showed better growth and mineralization of vertebrae, along with a lower incidence of skeletal anomalies compared to larvae fed with other diets. Moreover, the expression of bmp2, opn and oc was linearly related to mineralization of vertebrae. On the contrary, larvae fed diets non-supplemented with Zn (79 mg Zn/kg diet), showed an increase in the TBARS value, reduced growth, and a high incidence of severe skeletal anomalies denoting a deficiency in Zn. Besides, the highest dietary Zn levels (248 mg Zn/kg diet) also increased TBARS value and reduced larval growth. These results suggested that dietary Zn levels up to 110 mg/kg would be required by seabream larvae (36 dph) to promote growth, bone mineralization, protection from oxidation and prevent the prevalence of skeletal anomalies, whereas symptoms of Zn deficiency and excess were respectively found at 79 and 248 mg Zn/kg diet.