Vitamin D Levels in Sows from Five Danish Outdoor Herds

SIMPLE SUMMARY: A cross-sectional study on vitamin D(3) status was conducted in five Danish outdoor sow herds throughout August 2020. The aim was to determine the vitamin D status of outdoor sows during the peak sunshine season. The average 25-hydroxyvitamin D(3) concentration in serum was 67 ± 16 ng 25(OH)D(3)/mL in outdoor sows, which is considerably higher than levels found in sows housed indoors and fed a standard diet supplemented with vitamin D. ABSTRACT: Vitamin D is essential for sow health and productivity. Standard sow feed is therefore supplemented with vitamin D(3) or 25-hydroxyvitamin D(3) (25(OH)D(3)). However, it is uncertain whether the levels achieved are adequate for optimal performance. Currently, information on serum levels of vitamin D in pigs reared under both indoor and outdoor conditions is lacking. In August 2020, we obtained blood samples from 97 organic newly weaned sows housed outdoors during pregnancy and farrowing and used these to test for vitamin D in serum. The average concentration was 67 ± 16 ng 25(OH)D(3)/mL with a range of 32 to 134 ng 25(OH)D(3)/mL. The vitamin D(3) content was 21 ± 7 ng/mL, ranging from 9 to 48 ng/mL. The average number of hours of sun from June to August was 7.0 ± 0.5 h/day. Parity, farm and body condition score did not significantly affect serum levels of 25(OH)D(3).