Metabolic and production responses to calcidiol treatment in mid-lactation dairy cows

Abstract

The study of Vitamin D in cattle has often focussed on its role in calcium and mineral metabolism. However, there is evidence of a wider role for Vitamin D in bone and energy metabolism. Two studies were conducted to explore relationships between calcidiol supplementation, blood minerals and metabolites in mid-lactation dairy cows. In Experiment 1, a dose-response study was conducted in which 25 mid-lactation cows were fed one of five supplementary calcidiol doses (0, 0.5, 1, 2 or 4 mg calcidiol/day) for 30 days, with blood samples taken every 10 days. Increasing calcidiol dose increased plasma calcidiol (P = 0.001), 24,25-(OH) 2 -D 3 (P = 0.001) and serum phosphate (P = 0.003) in a curvilin..