“You can’t determine the severity of a calcium deficit just by looking at a cow,” said Luciano Caixeta, associate professor at the University of Minnesota. “So you don’t really know if she’s being affected by subclinical hypocalcemia, or how much it’s impacting her performance, if she is.”

Subclinical hypocalcemia reportedly affects as many as 73 percent of dairy cows on third or greater lactations and costs an average of $150 per case.

Mark van der List of Boehringer Ingelheim said, “It’s not a disease that’s going away, no matter an operation’s management style. Cows that are well-prepared for upcoming lactations will produce more colostrum, causing more calcium outflow to the mammary glands, putting cows at greater risk.”

The good news is more is known about managing subclinical hypocalcemia than ever before.

“Administering an oral calcium supplement to cows at calving, and again 12 hours later, provides much-needed calcium when blood levels are at their lowest,” van der List said. “The size of the supplement and the form of calcium are both important aspects for producers to consider when choosing a product.”

Caixeta said, “We did a study comparing boluses at the University of Minnesota, and feedback from my research team indicates that larger boluses are easier to administer to cows because they’re less likely to break or be spit back up and fall onto the floor.”

Van der List also encourages producers to read through the ingredients, and choose a bolus containing calcium chloride and calcium sulfate. Both of those forms of calcium are acidogenic, which will help fresh cows maintain adequate blood calcium levels. The calcium chloride will be rapidly absorbed, while the calcium sulfate will provide a sustained calcium release during the post-calving period.

Van der List said, “Watch out for products containing calcium carbonate [limestone] for supplementation. This is the cheapest form of calcium, and is too slowly absorbed to really make a difference in blood calcium levels. Some boluses will also contain other ingredients such as vitamin D, but fresh cows just need rapidly absorbed calcium from a quality bolus that’s easy to swallow.”

A recent study classified calcium levels in fresh cows -- second lactation and older -- into four categories.

1. Normal -- normal blood calcium levels on the first and fourth day after calving
2. Transient -- low blood calcium on the first day and normal on the fourth day after calving
3. Persistent -- low blood calcium on both the first and fourth day after calving
4. Delayed -- normal blood calcium on the first day and low on the fourth day after calving

Cows with transient hypocalcemia produced more milk than cows with normal blood calcium levels. Cows with persistent or delayed hypocalcemia were more likely to have an adverse event and may have benefited from oral calcium supplementation.

“We know regular blood calcium testing isn’t realistic for all dairy farms, due to the added labor and costs,” said van der List. “But testing could help us get a better sense of what’s going on with our fresh cows, so we can give them the right care.”

Ask a veterinarian about blood calcium testing. They can help evaluate the results and develop the right supplementation strategies for a herd.

More than 35 percent of all dairy cows have at least one clinical disease event during the first 90 days of milk, so it’s important to observe fresh cows daily.

Caixeta said, “Providing excellent fresh cow care sets cows up to do their job successfully. Since freshening is stressful, caretakers should be checking on fresh cows frequently to catch any surface-level problems that could end up affecting production down the road.”

Van der List advises observing the front and back ends of the cow twice per day.

Van der List said, “Check for nasal discharge, depressed attitude, low appetite, uterine discharge, udder and rumen fill, manure consistency, and hoof and leg health."

Both Caixeta and van der List agree managing hypocalcemia starts at dry off. To keep cows healthy through the dry period, consider several factors.

• Nutrition -- adopting a negative dietary cation-anion difference diet -- DCAD -- can help reduce the risk of subclinical hypocalcemia. “When you feed your cows a DCAD ration, it’s important to monitor urine pH to make sure the ration is achieving the desired effect,” van der List said. “I suggest testing urine pH at least once per week from 12 to 14 cows. Urine pH of cows consuming DCAD diets should be between six and seven for Holsteins and between 5.5 and 6.5 for Jerseys.”
• Heat abatement -- helping dry cows stay cool is just as important as keeping lactating cows cool. Dairy cows can experience heat stress beginning at 68 degrees Fahrenheit. Provide dry cows with proper shade, fans and sprinklers.
• Ventilation -- a well-ventilated building prevents high humidity in the winter and heat buildup in the summer. Signs of poor ventilation include air that smells like ammonia and animals coughing or experiencing nasal discharge or open-mouthed breathing. A cow’s hair coat should also be free of moisture.
• Stocking density -- dry cows require significantly more space than lactating animals. To ensure dry cows have enough space to eat and rest, keep stocking density at or less than 85 percent.
• Cleanliness -- remove manure as soon as possible, and keep plenty of fresh bedding under animals. Manage water tanks, feeding areas and walkways to eliminate standing water or manure.

A successful fresh cow program is a team effort. Caixeta and van der List encourage producers to work with a nutritionist and veterinarian to make a comprehensive fresh cow program unique to each herd’s needs. Visit boehringer-ingelheim.us for more information.