Preventing milk fever supports calcium balance and improves early lactation success
Getting dairy cows off to a strong start at the beginning of lactation is essential for long term health and productivity. One common challenge during this period is hypocalcemia, also known as milk fever, which occurs when blood calcium levels drop around calving.
“Historically, when we think of hypocalcemia, it’s those cows that go down and are unable to stand around the time of calving,” said Jen Roberts, DVM, Boehringer Ingelheim. “They may also have difficulty calving because they don’t have enough blood calcium for uterine contractions to deliver the calf. Those are the cows we see.”
Some cows show clear signs such as weakness, difficulty standing, or trouble calving. However, many cows experience subclinical hypocalcemia which shows no visible symptoms but still affects performance. These cows may eat less produce less milk and face higher risks of retained placenta and uterine infections.
“Subclinical hypocalcemia, by definition, is something you don’t typically see, especially in healthy cows, which are the most susceptible,” said Curt Vlietstra, DVM, Boehringer Ingelheim. “If you want to address it, you need to be aware that it is a problem.”
Because subclinical hypocalcemia is hard to detect, prevention is critical. Proper management during the pre-fresh period plays a major role in preparing cows for calving. Nutrition is especially important for older cows which are more likely to experience low calcium levels.
Many farms use a negative dietary cation-anion difference diet during the final weeks before calving. This approach helps prepare the cow’s body to better regulate calcium levels and reduces the risk of both clinical and subclinical hypocalcemia.
After calving blood, calcium levels typically reach their lowest point within 18 to 24 hours. Providing a fast-dissolving oral calcium bolus during this time helps support calcium needs and promotes a smoother transition into lactation. Offering a second bolus within 12 to 24 hours can provide added support especially for high-producing cows.
“After calving, supplementing cows with an oral, rapidly dissolving, readily available calcium bolus will help support their needs,” said Dr. Roberts. “If we’re not supporting those cows and providing additional calcium to keep them going smoothly through that transition, it can negatively impact their lactation and longevity in the herd. We need to ensure we provide supplemental calcium to support cows, so they can get lactation off to the best start.”
Choosing the right calcium bolus is also important. Acidogenic calcium sources such as calcium chloride and calcium sulfate are preferred because they are absorbed quickly and help the cow mobilize calcium from her bones. In contrast, calcium carbonate is absorbed more slowly and provides less support during this critical period.
High quality boluses with proper calcium ratios and a protective coating are easier to administer and safer for cows. When combined with balanced nutrition, these strategies help improve fresh cow health, reduce illness, and support strong milk production.
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