Milk Fever Prevention in High-Yielding Cows

Milk fever is a drop in blood calcium around calving, and high-yielding cows feel it hardest. Prevention is mostly about what you do in the dry period.

Key points

Milk fever is low blood calcium around calving, and mild cases are more common than obvious ones.
Restlessness, a stiff walk and a cow that goes down are signs to act on.
The close-up diet is the main prevention tool.
Test forages and check that cows actually eat the ration planned.
Call your vet for any down cow and follow withdrawal times.

What milk fever is

Milk fever, also called hypocalcemia, happens when a cow cannot replace blood calcium fast enough as she starts making milk. Calcium is needed for muscles to work, including the muscles of the gut, uterus and the heart. When levels fall, the cow weakens.

A cow that shows obvious signs, such as being unable to stand, has clinical milk fever. Many other fresh cows have a milder, hidden drop that does not look dramatic but raises the risk of other problems, such as retained placenta, displaced abomasum and mastitis.

Signs to watch

Early signs are easy to miss. The cow may be restless, nervous or shaky, with ears that are cool to the touch and an unsteady walk. Later she may go down, with her head turned back toward her flank and her body cool.

Every down cow needs prompt attention. Move her gently only if it is safe to do so, give her a place with good footing and call your vet. Do not try treatments from old supplies.

Restless or excited behavior
Stiff, wobbly walk
Reluctance to stand
Cool ears and body
Down with her head turned back
Poor appetite and little manure

Why high-yielding cows are at risk

A cow producing a lot of milk early in lactation draws a large amount of calcium into the milk in a short time. Older cows tend to be at greater risk than first-calf heifers because their ability to mobilize calcium from bone and absorb it from feed slows with age.

Breed, age, body condition and diet all shape risk. Your vet and nutritionist can tell you which cows in your herd deserve extra attention.

Prevention through the dry cow diet

The close-up diet is the main tool. Different approaches exist, such as limiting dietary calcium or managing the dietary balance of minerals. Which approach fits depends on your forages and your herd, so this is a decision for your nutritionist.

Whatever approach you choose, test your forages, mix the ration accurately and watch that cows actually eat it. Cows that sort feed or eat less than planned can end up with a ration that is not the one on paper.

Test forages for mineral content
Work with your nutritionist on close-up ration goals
Give plenty of bunk space and fresh feed
Avoid overfeeding in the dry period
Keep cows at a moderate body condition score on the one-to-five scale

Handling cows around calving

Calm, low-stress handling helps. Cows regroup, move and calve better when the close-up pen is comfortable, clean and not overcrowded. Provide fresh water, shade or ventilation as the season requires, and avoid sudden changes in diet.

Walk the close-up pen often so cows that are calving or looking odd are found early. Watch cows for the first day after calving more closely, since that is when the highest risk occurs.

What to ask your vet and nutritionist

Plan a visit before the next calving group. Bring forage test results, your close-up ration sheet and a list of cows with milk fever, retained placenta or displaced abomasum in the last year. Patterns in those lists help point to the cause.

A cow that stands after treatment is not automatically in the clear. Watch her intake, rumen fill and milk for the next several days, and tell your vet if she relapses or goes off feed. Cows that go down once are more likely to have other fresh problems, so keep her on the watch list and write notes in her record.

Which dry cow approach fits our forages?
Should we treat or screen older cows differently from heifers?
How should we handle a cow that goes down at night?
What records should we keep for each case?
Which other fresh cow diseases are linked to milk fever in our herd?

Common mistakes

Guessing at mineral levels without forage testing, changing the close-up ration without telling the nutritionist, and leaving down cows lying on slick concrete are frequent errors. Another is assuming a cow that gets up has recovered completely.

Any treated cow must have her milk and meat withheld for the time on the label or the time set by your vet. Record it clearly.

When to get help: Call your veterinarian immediately for a cow that is down or wobbly after calving, and do not delay for an overnight wait. Ask your nutritionist to review the close-up ration and forage tests if more than a rare cow is affected.

Sources and further reading

Organization homepages are linked so you can search them for current guidance on this topic.

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