Should I Use Intravenous Calcium to Prevent Subclinical Hypocalcemia?
Adapted by Ainhoa Valldecabres, VMTRC Researcher, Cedric Blanc, Cal-Poly & Noelia Silva del Río, UCCE Dairy Health Specialist
Hypocalcemia is an important postpartum metabolic disease. Although the use of anionic salts as a preventive strategy in prepartum diets has been widely implemented, hypocalcemia remains one of the most important postpartum diseases. In California's Central Valley the prevalence of clinical hypocalcemia when dietary cation-anion difference (DCAD) diets were fed has been reported to be 3%, whereas subclinical hypocalcemia (blood calcium < 8mg/dl) ranged from 14% to 67% for cows in their 2nd to 8th lactation.
Clinical and subclinical hypocalcemia have been associated with dystocia, retained placenta, metritis, endometritis, displaced abomasum, mastitis and decreased fertility. Based on data from the University of Wisconsin, the cost of this disease was estimated at $91,625/year for a 2,500 cow herd when clinical and subclinical hypocalcemia was 3% and 34%, respectively. Since there are no cow-side diagnostic tools to identify subclinical hypocalcemia, prevention is an important goal of transition cow programs. Postpartum calcium supplementation, administered intravenously (IV), orally and less frequently subcutaneously, is a strategy implemented on dairies to prevent subclinical hypocalcemia. However, calcium blood levels are influenced by the route of administration.
What happens to blood calcium levels after oral or IV calcium supplementation?
At UC Davis, we enrolled 33 multiparous crossbred cows (Jersey × Holstein) to evaluate the implications of giving IV Ca as a prophylactic strategy for hypocalcemia (Blanc et al., 2014, JDS). Cows were fed anionic salts in close-up diets and they were assigned to: control (receiving no calcium supplementation), IV calcium (Ca-IV; 500 ml of 23% Ca gluconate), or oral calcium (Ca-Oral; 2 Ca boluses 12 h apart) treatments. Treatment administration started within 6 h after calving. Blood samples for total serum calcium analysis were collected from calving to 48 h postpartum.
We observed that blood calcium spiked shortly after IV administration and it was higher than control cows or cows given oral calcium up to 4 h post-treatment. However, calcium levels rapidly declined and bottomed out at 24 h. Calcium levels were lower for cows given IV calcium compared to cows given oral calcium (at 20, 24 and 36 h postpartum) and control cows (at 36 and 48 h postpartum). It is likely that the initial spike in blood calcium downregulated calcium mobilization resulting in a temporary subclinical hypocalcemia.
Supplementation with IV calcium doesn't seem to have a positive effect on postpartum subclinical hypocalcemia prevention. Other routes of calcium administration might be more desirable. However, more research is needed to evaluate the impact of postpartum calcium infusions on health and production by IV, oral and subcutaneous routes.
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