Comparative Evaluation of Chemically Synthesized and Biosynthesized 25-Hydroxyvitamin D3 Supplementation in Sows During Late Gestation and Lactation

Vitamin D and its metabolite 25-hydroxyvitamin D3 (25-OH-D3) are central to calcium homeostasis, maternal skeletal integrity, and sow reproductive efficiency. This study compared vitamin D3 with an equivalent supranutritional dose of chemically or microbially produced 25-OH-D3 from day 90 of gestation to weaning. A total of 100 Large White × Landrace sows were assigned to five treatments (n = 20): a basal control (25 µg/kg vitamin D3), a VD3 group (basal + 50 µg/kg vitamin D3), and three 25-OH-D3 groups (basal + 50 µg/kg 25-OH-D3; QV1–QV3). Reproductive traits, colostrum composition, serum vitamin D-related indices, antioxidant and cytokine profiles, pre-weaning piglet growth, femoral mineral concentration, intestinal morphology, and barrier-related gene expression were assessed. Compared with the control, QV2 increased litter weight gain from birth to day 14 by 9.8%, piglet serum 25-OH-D3 at weaning by 33.2%, and femoral calcium concentration by 14.4% (p < 0.05); litter and average piglet weights at weaning were unchanged. Maternal 25-OH-D3 supplementation also altered the overall redox profile and several circulating inflammatory cytokines, increased jejunal and ileal villus height in the QV2 and QV3 groups, and upregulated selected tight-junction-related genes, including occludin and ZO-1, in a source- and intestinal-segment-dependent manner (p < 0.05). Responses were source-dependent, and QV2 showed the strongest effects for selected endpoints; the data do not support class-wide superiority of biosynthesized preparations.