Previous research has shown that feeding or injecting vitamin D prepartum can help improve cows’ calcium status and minimize hypocalcemia after calving. However, new research presented at the ADSA meeting this summer shows that prepartum vitamin D can also lead to negative health and production results.
In the study, German researchers evaluated the effects of an injection of vitamin D given intramuscularly at 275 days of gestation on cows’ blood mineral concentrations during the first 10 days in milk and on milk production and health in the subsequent lactation. All 375 Holstein cows enrolled in the study were fed a negative DCAD diet (-31 mEq/kg of DM) for the last 21 days of gestation and randomly assigned to either treatment (an injection of vitamin D) or control. In addition, levels of haptoglobin, NEFA, BHB and 25-(OH) vitamin D concentrations were checked in a subset of 100 cows. Compared to control cows, results for vitamin D treated cows showed that:
- Serum concentration of 25-(OH) vitamin D was increased on days 1, 5 and 10 after calving.
- Blood calcium and phosphorous concentrations were significantly elevated through each of the first 10 DIM.
- Magnesium concentration was significantly lower during the first 10 DIM.
- Haptoglobin concentrations were significantly higher on day 5.
- NEFA levels were elevated.
- There was a numerically higher incidence of retained fetal membranes and increased risk for clinical metritis.
- Treated cows produced less milk. Energy corrected milk was down 8.8 lbs/day on first test day and 5.6 lbs/day on second test day.
- Time to pregnancy was 27 days longer in treated cows.
Venjakob et al., 2021. J. Dairy Sci. Vol 104, Suppl. 1 #327.