Salmonid farmed fish are one of the important sources of vitamin D in the human diet; however, the level of vitamin D in their flesh strongly depends on feed formulation. Given recent changes in European Union regulations and the increased permitted limit of vitamin D3 in feed, there is a growing need to evaluate the efficiency of vitamin D transfer from feed to fillet.
In this study, it was examined how different levels of synthetic vitamin D3 (cholecalciferol) affect the accumulation of vitamin D3 in the whole body and fillet of trout.
The research was conducted in 2022 over a 61-day feeding trial.
Ten diets with increasing levels of vitamin D3 ranging from 8,100 to 77,400 IU/kg feed were used in the experiment.
Growth performance, nutrient retention, and flesh color parameters were evaluated to determine the safety and efficiency of this supplementation.
Results
- Growth performance
Increasing vitamin D3 in the feed had no negative or positive effect on growth, feed intake, specific growth rate, or feed conversion ratio. This indicates that the tested levels are completely safe. - Vitamin D3 accumulation
Although growth remained unchanged, increasing vitamin D3 led to a strong linear increase in vitamin D levels in both fillet and whole body. These findings confirm the use of feed fortification strategies to improve the nutritional value of the final product. - Fillet color and meat quality
Color measurements (MINOLTA a) showed a slight increase in fillet redness with higher vitamin D3 levels, but this effect was not statistically significant. Overall, vitamin D3 supplementation preserved the visual quality of the fillet.
Conclusion
- By increasing dietary vitamin D3, trout fillets can be effectively enriched with vitamin D3.
- This increase occurs without any impact on growth, health, or feed efficiency.
- Such an approach can help address vitamin D deficiency in human nutrition and increase the market value of the product.
- This study highlights that targeted fillet fortification with vitamin D3 is a sustainable and effective strategy in aquaculture nutrition and public health.