FROM THE FARM REPORT: CALCIUM AND INFLAMMATION

The period around calving is one of the most physiologically challenging phases in a cow’s life. As lactation begins, the cow’s calcium demand increases substantially. During this time feed intake is relatively low, making it more difficult for a cow to meet her nutritional needs. One key challenge is maintaining an adequate blood calcium concentration. While clinical hypocalcemia (i.e., milk fever) is usually well-managed in most dairy herds today, subclinical hypocalcemia (SCH) – characterized by low blood calcium without obvious clinical signs – is more common and harder to detect.

Calcium Matters

At calving a cow’s calcium demand increases by 2 to 3 times. This is primarily due to the onset of milk production, but calcium is also needed for muscle function, immune response, and other metabolic processes. If dietary intake and bone resorption of calcium can’t meet this demand, blood calcium concentration will drop. Subclinical hypocalcemia is associated with a greater risk of lower feed intake, poorer milk production, infertility, and diseases like metritis and mastitis. A recent study from the Overton lab at Cornell University (Graef et al., 2025; https://doi.org/10.3168/jds.2024-25979) explored how different patterns of low blood calcium relate to inflammation and performance of Holstein cows during early lactation. These insights can help farmers make informed decisions about nutrition and herd management.

Calcium Patterns in Fresh Cows

In the Cornell study, 96 2nd and greater lactation cows were grouped retrospectively based on their blood calcium concentration at 1 and 5 days in milk (DIM):

Normal calcemic (NC): blood calcium > 1.95 mmol/L at 1 DIM and > 2.32 mmol/L at 5 DIM (n = 53 cows)

Transient SCH (tSCH): blood calcium <1.95 mmol/L at 1 DIM and >2.32 mmol/L at 5 DIM (n = 15 cows)

Delayed SCH (dSCH): blood calcium >1.95 mmol/L) at 1 DIM and <2.32 mmol/L at 5 DIM (n = 15 cows)

Persistent SCH (pSCH): blood calcium <1.95 mmol/L at 1 DIM and <2.32 mmol/L at 5 DIM (n = 13 cows).

These patterns help identify cows that are more likely to struggle during early lactation. Previous research from the McArt lab at Cornell University has shown that cows with dSCH or pSCH produced less milk and experienced more health problems.

Inflammation

Inflammation is a normal physiological response after calving, but excessive or prolonged inflammation can be harmful. The Cornell study found that calcium status after calving was not related to inflammation markers (i.e., acute phase proteins and cytokines) in blood the day before calving. However, cows with pSCH had higher inflammation markers – especially haptoglobin (Hp) and serum amyloid-A (SAA) in the blood during the first week after calving. This suggests that cows recovering quickly from low blood calcium may be better at managing stress and inflammation.

Performance

Before calving, tSCH cows ate more feed than nSCH and pSCH cows. Over the first 9 weeks of lactation, feed intake of cows increased steadily and was not affected by calcium status. Although pSCH cows ate less than other cows during a few days in the first 3 weeks. Energy-corrected milk yield during the 1st 9 weeks of lactation was greatest for the tSCH cows and lowest for the pSCH cows. The cows with pSCH not only had higher inflammation but also ate less and produced less milk. These findings reinforce the link between calcium status, inflammation, and performance.

Practical Actions for Farmers

To support cows during the transition period, consider the following strategies:

Implement a close-up diet that uses either a negative DCAD approach with anionic salts or a mineral binder to prevent or minimize the duration of SCH.

Test blood calcium at 1 and 4-5 DIM to identify cows at risk.

Support the immune system by feeding appropriate amounts of minerals, vitamins, and antioxidants as well as by minimizing environmental and social stressors.

Watch for signs of excessive or prolonged inflammation and monitor herd health closely.

Not all cases of low calcium are the same. Some cows recover quickly and do well, while other cows will remain low and have more problems. By understanding calcium dynamics and implementing proactive nutritional and management strategies, farmers can improve cows’ feed intake, milk production, and health. Continued research will refine SCH diagnostics and improve fresh cow care.

— Heather Dann

dann@whminer.com