Ketosis
At a glance
Ketosis occurs when cows cannot meet their energy needs after calving and mobilise body fat to make up the shortfall. That creates high levels of ketones and can cause poor appetite, weight loss, reduced milk, and increased risk of other metabolic and infectious problems. Subclinical ketosis is common and often hidden, but it still reduces production and fertility. Focus on prevention through feeding and management in the close-up period and early lactation, and act quickly if multiple cows show signs.
For more on ketosis, watch our webinar – Setting the cow up for success- Ketosis
Symptoms
- Reduced feed intake
- Slow eating
- Decreased milk yield and butterfat content
- Loose manure with undigested grain
- Discomfort, kicking at the stomach, restlessness
- Increased lameness
What you might notice on-farm
Signs of clinical ketosis
- Reduced appetite or off feed, particularly for grain and high-energy supplements
- Rapid loss of condition or bodyweight in the first weeks after calving
- Dullness, separation from the mob, and decreased milk yield
- Sweet or acetone smell on the breath or urine in severe cases
- Nervous signs in extreme, untreated cases
Signs of subclinical ketosis
- No obvious clinical signs, but lower milk production than expected for the herd or reduced reproduction performance
- Increased risk of retained placenta, displaced abomasum and metritis in affected cows
- Herd-level patterns such as many cows with low peak milk, slow rising yields or poor submission rates
If you suspect ketosis in individual cows, test for ketones using milk or blood strips to confirm.
For more – Understanding subclinical ketosis in New Zealand’s dairy cows
What good looks like
Targets and signs of a well-managed transition:
- Low herd incidence of clinical ketosis and minimal loss of condition in early lactation
- Herd-level ketone prevalence below locally accepted thresholds for subclinical ketosis (work with your adviser or vet for targets)
- Strong dry cow and close-up feeding plans that maintain steady intake and avoid sudden dietary shifts at calving
- Early identification and treatment of clinical cases and monitoring of high-risk groups, such as older cows, thin cows, and high-yielders
Follow these quick checklists
What to do today
- Walk the yard and note cows off feed, dull or isolating themselves and flag them for testing.
- Check recent condition scores for trends. Are cows losing condition before or after calving?
- Review feeding of the close-up mob. Is intake steady, and are cows getting a reliable energy source?
- Confirm water and feed access is not restricted, and reduce competition for shy eaters.
What to do this week
- Test a sample of fresh calved cows for ketones to see if subclinical levels are present at the herd level.
- Review ration energy density and form, close-up diets should support steady intake rather than sudden high-energy spikes.
- Identify high-risk groups: older cows, very high yielders, cows that calved thin, and cows with other calving issues.
During early lactation
- Monitor feed intake daily and watch for drops around calving.
- Treat clinical cases promptly with veterinary guidance. Mild cases often respond to oral propylene glycol and supportive feeding; follow your vet or adviser plan.
- Re-check cows that were treated and monitor milk yield recovery.
Issues, likely causes and where to start
If multiple cows have ketosis, treat it as a system failure rather than random bad luck. Common causes and first checks:
If many cows have low appetite after calving
Likely causes:
- Sudden diet change at calving, especially from high-fibre to high-energy mixes
- Inadequate fibre leading to rumen instability
- Poor water access or heat stress reducing voluntary intake
Start with:
- Check recent feeds and the timing of any changes; avoid abrupt diet swaps at calving.
- Confirm water flow and trough access.
- Improve fibre consistency in the close-up ration to maintain rumen function.
If cows are losing condition quickly after calving
Likely causes:
- Negative energy balance driven by underfeeding in the close-up period or very high yielders not meeting needs
- Suboptimal body condition at calving, either too thin or too fat
- Illnesses reducing intake, such as mastitis or calving injuries
Start with:
- Re-score cows and check the distribution of condition, then separate thin animals for targeted feeding.
- Check feed test results and calculate likely intake versus energy requirement.
- Investigate other health issues that reduce appetite.
If herd fertility or milk yields are down
Likely causes:
- High subclinical ketosis prevalence reducing production and reproductive performance
- Inadequate transition management and poor early-lactation intake
Start with:
- Do a herd ketone screen and compare results to past seasons.
- Tighten the transition plan: steady diets, monitored intake, and targeted support for high-risk cows.
When to call the vet
Call your vet promptly if:
- You have multiple cows with clinical signs that do not respond to on-farm treatment within 24 to 48 hours
- You see sudden deaths, severe nervous signs, or cows going down acutely
- Herd-level testing shows a high prevalence of subclinical ketosis combined with poor production or fertility trends
- You need assistance with herd testing, treatment protocols, or necropsy of unexplained deaths
How minerals fit in
Minerals and trace elements do not prevent ketosis on their own, but they support metabolic health and appetite. Correcting mineral gaps is part of a broader transition plan.
How minerals help on-farm
- Magnesium supports normal rumen function and appetite and can reduce the risk of hypomagnesaemia at turnout or when diets change.
- Balanced macro and trace minerals support immune function, tissue recovery and enzyme systems involved in energy metabolism.
- Delivery matters. Make sure minerals reach the cows that need them most by matching delivery method to your system and mob structure.
Practical mineral checks
- Review where minerals are offered and who is likely to miss out. Shy feeders and low-rank cows often fail to consume free-choice supplements.
- If you feed bespoke close-up rations, include minerals in a way that maintains palatability and intake.
- Work with your adviser or vet to test for common deficiencies if you suspect mineral-driven appetite or health issues.
FAQs
How soon after calving does ketosis usually show?
Ketosis most often appears in the first two to four weeks of lactation, but subclinical ketone levels can be detected at or shortly after calving.
What simple on-farm test can I use for ketosis?
Milk or blood ketone test strips are a practical on-farm option for screening individual cows. Bulk milk testing is less useful for early detection.
Can cows recover fully from ketosis?
Yes, many cows recover with prompt treatment and management. Untreated or repeated cases reduce milk yield and fertility and increase the risk of other diseases.
Will feeding more concentrates prevent ketosis?
Not on its own. Sudden high-concentration intake can cause rumen instability. Prevention is about steady intake, correct fibre, gradual changes and targeted support for high-risk cows.
Should I screen for subclinical ketosis herd-wide?
Screening a representative sample of fresh cows is a useful diagnostic step if you have production or fertility concerns. Work with your vet or adviser to interpret results and set thresholds for action.
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