Interaction between vitamins A and D on growth and metabolic responses of abalone Haliotis discus hannai, INO

A 152-day growth experiment was conducted in a recirculated water system to investigate the interaction between vitamins A (retinol) and D (cholecalciferol) on growth and metabolic responses in abalone Haliotis discus hannai Ino. Triplicate groups of juvenile abalone (initial weight: 0.35 ± 0.03 g; initial shell length: 11.31 ± 0.25 mm) were fed to satiation one of 16 semipurified diets containing 0, 1 × 10³, 1 × 10⁵, 1 × 10⁶ IU/kg vitamin A and 0, 500, 1 × 10³, 5 × 10³ IU/kg vitamin D in a 4 X 4 factorial design. Abalone were weighed and shell-length measured on the 76th day and the 152nd day, respectively. The total specific growth rate (SGR) during the 152 days, neither the SGR in the first 76 days nor in the second 76 days, was significantly influenced by the interaction between vitamins A and D. Dietary vitamins A and D significantly stimulated viscera 25-hydroxyvitamin D ₃ [25(OH)D₃] and 1α,25-dihydroxyvitamin D ₃ [1α,25(OH)₂D₃] contents in a cooperative fashion. Dietary vitamin A generally increased the alkaline phosphatase (AKP) activity in viscera except the excessive supplement (1 × 10⁶ IU/kg), which significantly decreased AKP activity. Dietary vitamin D significantly increased AKP activity. Contents of P, not Ca and Mg, in soft body increased with dietary vitamin D supplement. Dietary vitamin A significantly improved contents of lipid and retinol in soft body and viscera, respectively. Meanwhile, dietary vitamin D significantly increased contents of ash and cholecalciferol in soft body and viscera, respectively. Based on these results, interaction between vitamins A and D was expressed in various manners as different indicators were considered, though there was potential antagonism mechanism at molecular level between the two fat-soluble vitamins.