Active D: An innovative natural solution to prevent hypocalcemia in dairy cows

Santiago Bas, DVM, PhD



Hypocalcemia is a common metabolic disorder of periparturient dairy cows particularly affecting high producing pluriparous animals. As the end of gestation approaches, calcium demands start to increase due to the final development of the fetal skeleton and the initiation of the synthesis and accumulation of maternal colostrum. By the onset of lactation, the demands of calcium are dramatically increased as cows start producing and secreting large amounts of colostrum. While the bovine fetus requires 10.3 gr of calcium by the end of gestation, the calcium requirements to produce 10 kg of colostrum are more than doubled and can be as high as 23 gr (Figure 1). Additionally, as lactation progresses, calcium demands for milk production continue to increase to meet the cow needs for milk synthesis. Consequently, cows will remain in a negative Ca balance during the first 6-8 weeks of lactation, and it has been estimated that about 13% of the Ca skeleton is lost (Figure 1).

Figure 1. Milk yield and plasma total Ca relative to calving date in dairy cows


Based on the presence of clinical signs, hypocalcemia can be classified as clinical and subclinical. Clinal cases occur within the first 72 h following parturition, with more than 75% of the cases typically observed 24 h after calving. Cows that experience clinical hypocalcemia are observed recumbent with an auto-auscultatory position and cold ears. In contrast, in dairy cows with subclinical hypocalcemia no clinical signs are observed. Thus, for identification of animals suffering the subclinical form of the disease, blood samples need to be collected to determine circulating calcium concentrations. Regardless of the clinical classification, hypocalcemia is considered as a getaway disease that has been associated with increased risk various of postpartum metabolic and infectious diseases and impaired productivity and fertility. In this context subclinical hypocalcemia has major economic consequences as it is a prevalent condition that can affect more than 50% of the cows in a herd.

More recently the concept of calcium dynamics was introduced to describe the changes in calcium concentrations in the first 4 days of lactation (Figure 2). Based on calcium concentrations at different times pluriparous dairy cows can be classified into one of 4 categegories: normocalcemic, transiently hypocalcemic, persistently hypocalcemic or delayed hypocalcemic (Figure 2).

Figure 2. Circulating calcium dynamics in post-partum dairy cows


Normocalcemic and transiently hypocalcemic cows can be further classified as eucalcemic while persistently and delayed hypocalcemic cows are classified as dyscalcemic. More than blood calcium concentration thresholds, the changes in blood calcium in the first days in milk is more relevant for the classification of cows into on the groups. Based on the changes in circulating calcium concentrations it seems that lower calcium by 4 DIM is associated with increased risk of disease, lower milk yield and impaired reproductive performance. Thus, strategies that enhance calcium absorption in the first days following parturition are critical.

Active D is an effective and practical solution that can be implemented for the control of hypocalcemia in dairy cows. Active D is an innovative herbal formulation which contains natural vitamin D glycosides that promote the absorption of dietary calcium from the digestive tract, stimulates calcium release from the bones and strengthens the immune system. Active D is available for inclusion in the feed or in the form of boluses. Active D boluses were designed using cutting edge technology that allows the release of the active ingredients over a period of 3 days allowing the cow to maintain elevated calcium concentrations in the first week post-partum. This innovative solution has the advantage that only one application is needed after parturition, as opposed to other solutions that require more than one application.

Results from a field trial showed that Active D increased circulating ionized calcium concentrations in pluriparous post-partum dairy cows relative to non-supplemented controls on lactation days 1, 3 and 7 (Figure 3).

Figure 3. Circulating ionized calcium concentration in dairy cows supplemented with Active D boluses relative to untreated control cows

Additionally, a recent study that looked into performance showed that cows supplemented with Active D boluses at parturition yielded more milk, had reduced SCC and less proportion of cows with SCC above 200,000 (indicative of subclinical mastitis). Furthermore, there were less cows diagnosed and treated for clinical mastitis in the Active D group when compared to cows in the control group.

Active D is an effective natural strategic solution that can be easily implemented on farms to enhance the absorption of calcium from the gut and calcium resorption from the bones, allowing the cow to meet the calcium demands system during the periparturient period. Additionally, Active D boosts the immune system allowing a successful transition of cows from gestation to lactation and promoting a healthy and productive life.

- Santiago Bas, DVM, PhD