Effects of Dietary 25-Hydroxycholecalciferol Alone or in Combination with Vitamin D3 on Growth Performance, Blood Vitamin D Status, Immune Response, Bone Integrity, and Antioxidant Capacity of Nursery Pigs.

This study evaluated the effects of dietary 25-hydroxycholecalciferol alone or in combination with vitamin D3 (VD3) on growth performance, vitamin D status, immune parameters, bone integrity, and antioxidant capacity in nursery pigs. Sixty weanling piglets (5.63 ± 0.98 kg initial body weight) were assigned to three treatments for a 28 d feeding trial. The treatments were a basal diet supplemented with 2000 IU/kg VD3, a combination of 1000 IU/kg VD3 and 1000 IU/kg 25-hydroxycholecalciferol (25-OHD3), and 2000 IU/kg 25-OHD3. Pigs fed diets containing 25-OHD3 tended to have greater feed intake during d 14-28 (p = 0.06). Plasma 25-OHD3 concentrations were greater in pigs fed diets containing 25-OHD3 than in those fed VD3 alone on d 14 and 28 (p < 0.05), with greater values observed in pigs fed 2000 IU/kg 25-OHD3 than in those fed a combination of 1000 IU/kg VD3 and 1000 IU/kg 25-OHD3 on d 14 (p < 0.05). Pigs fed diets supplemented with 25-OHD3 had lower plasma malondialdehyde concentrations at d 28 (p < 0.05), while immune parameters and bone mineralization indicators were unaffected. In the broken-line analysis, the estimated plasma 25-OHD3 concentration for plasma malondialdehyde concentrations to reach the minimum level was 32.5 ng/mL (p < 0.05). In conclusion, supplementing 25-OHD3 in nursery diets improved blood vitamin D status and could help reduce oxidative stress during the late nursery period.