25-hydroxyvitamin D3 affects vitamin D status similar to vitamin D3 in pigs--but the meat produced has a lower content of vitamin D.

In food databases, the specific contents of vitamin D-3 and 25-hydroxyvitamin D-3 in food have been implemented in the last 10 years. No consensus has yet been established on the relative activity between the components. Therefore, the objective of the present study was to assess the relative activity of 25-hydroxyvitamin D-3 compared to vitamin D-3. The design was a parallel study in pigs (n 24), which from an age of 12 weeks until slaughter 11 weeks later were fed approximately 55 mu g vitamin D/d, as vitamin D-3, in a mixture of vitamin D-3 and 25-hydroxyvitamin D-3, or 25-hydroxyvitamin D-3. The end-points measured were plasma 25-hydroxyvitamin D-3, and in the liver and loin the content of vitamin D-3 and 25-hydroxyvitamin D-3 Vitamin D-3 and 25-hydroxyvitamin D3 in the feed did not affect 25-hydroxyvitamin D-3 in the plasma, liver or loin differently, while a significant effect was shown on vitamin D-3 in the liver and loin (P<0.001). 25-Hydroxyvitamin D-3 in the plasma, liver and loin significantly correlates with the sum of vitamin D-3 and 25-hydroxyvitamin D3 in the feed (P<0-05). Therefore, 25-hydroxyvitamin D-3 should be regarded as having the same activity as vitamin D-3 in food databases. Sole use of 25-hydroxyvitamin D-3 as a vitamin D source in pig feed will produce liver and meat with a negligible content of vitamin D3, while an increased content of vitamin D-3 in the feed will produce liver and meat with increased content of both vitamin D-3 and 25-hydroxyvitamin D-3.