Dietary vitamin D3 affects digestive system ontogenesis and ossification in European sea bass (Dicentrachus labrax, Linnaeus, 1758)

The influence of dietary vitamin D3 (VD3) on survival, growth and morphogenesis during the larval development of European sea bass (Dicentrarchus labrax) was evaluated until 45 days post hatching. Diets contained 4% of the standard vitamin mix (VM) recommended by the National Research Council (NRC) and incorporated 0, 19.2, 38.4, or 140 IU of VD3 per gram of diet to give VD-0, VD-1, VD-2 and VD-3 dietary treatments, respectively. The present study revealed for the first time an impact of dietary VD3 on the sea bass digestive system ontogenesis that consequently conditioned the ossification process and morphogenesis. All dietary VD3 levels were in the “adequate range” based on larval survival. Nevertheless, growth, intestinal maturation and ossification at the end of the larval stage were harmed by the minimum dose of VD3 tested and resulted in the appearance of malformations. VD-2 and VD-3 groups showed satisfactory growth and ossification levels at the end of the larval period. However, results of enzymatic activity and expression of genes involved in the VD3 pathway (bone morphogenetic protein 4, osteocalcin, vitamin D receptors and transient receptor potential cation channel-subfamily V, member 6-) gave evidence of complications during the ossification process as revealed by the high percentage of deformed larvae. A VD3 level of 19.2 IU/g diet appeared necessary to obtain harmonious larval morphogenesis.