# Balancing Dietary Vitamin D3 and Phosphorus Improved Growth, Mineralization, and Fecal Characteristics of Atlantic Salmon (Salmo salar) Post-Smolts in Land-Based Aquaculture

## TL;DR

Balancing vitamin D3 and phosphorus in diets improves growth, bone health, and waste in farmed Atlantic salmon.

## Contribution

Identifies optimal vitamin D3 and phosphorus levels to enhance growth and reduce environmental phosphorus load in aquaculture.

## Key findings

- Growth improved with moderate vitamin D3 and phosphorus but declined with excessive levels.
- High vitamin D3 reduced bone ash, but intermediate levels maintained bone mineralization.
- Increased vitamin D3 reduced fecal phosphorus, aiding waste management in aquaculture.

## Abstract

Metabolic responses to different dietary levels of vitamin D3 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 D3 and avP. In summary,growth performance, measured as specific growth rate (SGR), improved when either vitamin D3 or avP was increased independently, but declined when both were elevated excessively. Bone mineralization was maintained at intermediate vitamin D3 inclusion levels, though high vitamin D3 reduced bone ash. A diet containing 0.63 mg/kg vitamin D3 and 0.70% avP supported growth and mineral retention. A significant reduction in fecal soluble phosphorus when vitamin D3 was increased in the diet, suggests that management of vitamin D3 can contribute to improved waste control and reduced environmental load for phosphorus. Finally, the study highlighted that today's commercial dietary inclusion of vitamin D3 can result in lower vitamin D3 accumulation in muscle of land-based farmed Atlantic salmon compared to wild Atlantic salmon.