Ashleigh Currie

Metabolic responses to different dietary levels of vitamin D ₃ and available phosphorus (avP) was investigated in cultured Atlantic salmon ( Salmo salar ). The study was carried out in triplicate with a 2‐level full factorial design with a center point and three additional points within the design space. Over a 17‐ week period at the initial weight of 453 ± 9 g, salmon reared indoor on land, were fed diets containing different levels of vitamin D ₃ and avP. In summary,growth performance, measured as specific growth rate (SGR), improved when either vitamin D ₃ or avP was increased independently, but declined when both were elevated excessively. Bone mineralization was maintained at intermediate vitamin D ₃ inclusion levels, though high vitamin D ₃ reduced bone ash. A diet containing 0.63 mg/kg vitamin D ₃ and 0.70% avP supported growth and mineral retention. A significant reduction in fecal soluble phosphorus when vitamin D ₃ was increased in the diet, suggests that management of vitamin D ₃ can contribute to improved waste control and reduced environmental load for phosphorus. Finally, the study highlighted that today’s commercial dietary inclusion of vitamin D ₃ can result in lower vitamin D ₃ accumulation in muscle of land‐based farmed Atlantic salmon compared to wild Atlantic salmon.