Interaction between Dietary Vitamin D 3 and Vitamin K 3 in Gilthead Seabream Larvae ( Sparus aurata ) in Relation to Growth and Expression of Bone Development-Related Genes.

Vitamins D and K are essential fat-soluble nutrients that intervene in bone development processes among other biological functions. The present study is aimed at investigating the potential combined effect of dietary supplementation with vitamin D 3 (cholecalciferol) and vitamin K 3 (menadione) in gilthead seabream ( Sparus aurata ) larvae. For that purpose, seabream diets were supplemented with different combinations of vitamin D 3 /vitamin K 3 (mg/kg diet) as follows: 0.00/0, 0.06/70, 0.06/170, 0.13/70, 0.13/170, 0.40/70, and 0.40/170. Feeding gilthead seabream larvae (22 days post hatch) for 21 days with the diets supplemented with 0.06-0.13 mg/kg vitamin D 3 and 70 mg/kg vitamin K 3 (diets 0.06/70 and 0.13/70) led to the highest larval growth and survival and the highest expression of important biomarkers of both bone development and health, such as bmp2 , osx , and mgp , and calcium homeostasis, such as pthrp and casr . However, the increased supplementation with both vitamins at 0.40 mg/kg vitamin D 3 and 170 mg/kg vitamin K 3 (diet 0.40/170) reduced larval growth and survival, downregulated bmp2 and pthrp expressions, and upregulated osx and mgp , causing an unbalance in the relative expression of these genes. The results of the present study have shown the interaction between vitamin D 3 supplementation and vitamin K 3 supplementation in larval performance and gene expression related to bone development and calcium homeostasis, denoting the significance of a correct balance between both vitamins in larval diets.