Dietary levels of vitamins D and K on growth, calcium metabolism and skeletal health in gilthead seabream (Sparus aurata)

Abstract

Vitamin D is an essential fat soluble micronutrient that helps in growth, bone development, calcium homeostasis and other metabolic process. The study on effect of vitamin D3 in marine fish larvae were very scarce irrespective of species. The present study determines the impacts of dietary vitamin D3 on growth performance, calcium absorption, mineralization, and skeletal anomalies during the development of gilthead seabream (Sparus aurata) larvae was assessed until 47 days post hatching. Diets containing four levels of vitamin D3 (0, 25, 30, 384 μg kg-1 or 11.6, 1000, 1200, 15360 IU kg-1) were formulated to determine the effect of vitamin D3 at deficient, excess, and optimum levels. The gilthead seabream larvae in the present study fed with this wide range of vitamin D3 presented a constant growth with all the diets but presented signs of toxicity in excess level, affecting the survival, calcium uptake, and bone biomarker mechanism in larvae, which resulted in increased skeletal anomalies and mortality. An increase of dietary vitamin D3 up to 384 μg kg-1 significantly raised the whole body vitamin D3 content, calcium, and phosphorus intake and increased the incidence of skeletal anomalies, particularly cranial anomalies. The appearance of skeletal anomalies in larvae fed 384 μg kg-1 vitamin D3 was in association with the upregulation of bmp2, alp, and oc gene expression. However, larvae fed 0, 25, 30 μg kg-1 vitamin D3 showed higher survival than the group fed 384 μg kg-1 vitamin D3. Meanwhile vitamin D3 deficient diet 0 μg kg-1 presented with lower mineralization rate and increase incidence of maxillary anomaly. Thus, the current study revealed the evidence of vitamin D3 deficiency as well as toxicity in gilthead seabream larvae during the developmental process and conclude that the recommended dietary vitamin D3 level for gilthead seabream larvae may range between 25 and 30 μg kg-1 which improves larval survival, calcium and phosphate level and vertebral mineralization with reduced incidence of skeletal anomalies in gilthead seabream larvae