Effect of vitamin D treatments on plasma metabolism and immune parameters of healthy dairy cows

ABSTRACT

The objective of this study was to investigate the possible beneficial effect of vitamin D repletion on certain immune parameters of vitamin D insufficient dairy cows. Twenty dairy cows in late lactation were treated daily with vitamin D in five different ways: sunlight exposure (SUN), D₂ supplementation combined with sunlight exposure (D2SUN), D₂ supplementation (D2), D₃ supplementation (D3), and D₂ and D₃ supplementation combined (D2D3). The cows had very low vitamin D levels at d 0 because of the vitamin D deprivation before the study. After 1 month of vitamin D repletion, all cows had plasma 25(OH)D levels within the normal range. Total 25(OH)D concentration was significantly higher in SUN, D2SUN and D2D3 than D2 or D3 at the end of the study. However, milk yield, as well as protein and fat content of the milk, was not influenced by vitamin D treatments. There was no difference obtained in the measured immune parameters: Leucocyte populations, somatic cell count, immunoglobulin concentrations in plasma and milk, and antigen-stimulated cytokine productions did not change in response to vitamin D repletion or difference in vitamin D sources, and no relations to plasma 25(OH)D levels were identified. Despite the fact that plasma 25(OH)D increased from a very low level to normal range, the present study did not show any effect of vitamin D repletion on the tested immune parameters of healthy dairy cows. Therefore, in this study, it was concluded that repletion to physiologically normal plasma 25-hydroxyvitamin D levels of vitamin D-depleted healthy dairy cows had no influence on immune parameters.

KEYWORDS:

• Cholecalciferol
• cows
• ergocalciferol
• immune competence
• sunlight
• supplements
• vitamin D

Acknowledgements

The authors thank laboratory technicians E.L. Petersen, M.W. Reeh, I.M. Jepsen, H.M. Purup and Research technician T.N. Jakobsen for assistance during blood sampling and laboratory analyses. The authors also thank senior researcher R. Labouriau in the Department of Mathematics, Aarhus University for his help with statistical analyses.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The experimental study was financed via a grant from the Danish Council for Independent Research –Technology and Production (DFF–FTP) under the Danish Ministry of Higher Education and Science [grant number 12-131938] obtained by L. Hymøller.