Evaluation of plasma biotin, folate, and vitamin B12 concentrations of Holstein dairy cows fed adequate or high concentrations of dietary vitamin D3, vitamin E, calcium, and selenium under heat stress

Abstract

The aim of this study was to determine plasma biotin (B8), folate (B9), and vitamin B12 (B12) concentrations of multiparous dairy cows under heat stress (HS) fed with adequate or high concentrations of vitamin D3 (VITD) and E (VITE), Ca, and Se. Twelve multiparous Holstein cows were used in a split-plot design. The main plot was: (1) Adequate VITE and Se; (2) High VITE and Se. Within each main plot, cows were assigned to treatments: (1) HS with adequate concentrations of VITD and Ca; (2) HS with high concentrations of VITD and Ca; (3) pair-feeding (PF) with HS in thermoneutrality with adequate concentrations of VITD and Ca in a duplicated 3 × 3 Latin square. There were no treatment effects on plasma B8 and B12. Plasma B9 was lower by 21% for HS with adequate VITD and Ca than PF cows. Results suggested that HS might modify folate status in dairy cows, regardless of treatments.