Milk fever - Early intervention can pay big dividends in calcium-deficient cows
There are huge demands for calcium in a cow close up to and particularly at calving and it plays a huge role in muscle formation and immunity.
There are some complex hormonal interactions which allow the cow draw huge amounts of calcium from the bones to the blood while she adapts to her new diet. There can be some complex interactions here but by monitoring certain things we can address the problem.
Calcium plays a huge role in muscle function and immunity. The classic milk fever cow is down with often her head turned back into her body or in later stages out flat and unable to rise.
This can be very easy to identify as milk fever but what we often don't see is cows with subclinical milk fever. This can predispose cows to a whole range of diseases because of immuno-suppression. It can often cause an increase in uterine infections or in clinical mastitis in the first 30 days after calving.
Milk fever rates should not exceed 2pc - anything above this requires intervention. This is because this figure simply the tip of the iceberg and would indicate many more cows will be affected with subclinical milk fever.
Treating individual cows with milk fever involves intravenous calcium borogluconate slowly.
The calcium should be at body temperature to aid absorption, especially when given ubder the skin. There are also options of using calcium boluses to cows that are at risk (one at the point of calving and one after calving).
Never presume a dower cow has milk fever. Always check for mastitis or other injuries etc. that might be causing the cow to be down. Some cows down with milk fever can respond poorly to calcium because of other issues and these cases should be investigated and treated by your vet. Always try and prop these cows up to prevent aspiration pneumonia or bloating.
When we see an increase of diseases like we mentioned previously or cases of milk fever it should automatically switch our attention to herd control of calcium.
Cows should be on a low level of calcium (ideally<30g/day) and high level of Magnesium (ideally >40g/day or >0.4pc of DMI) in the run-up to calving. When presented with milk fever issues we often initially will look at dry cow condition. If cows have a BCS of 3.5 or greater they are potentially more at risk of milk fever. It is critical to review the forages looking at calcium, magnesium and potassium levels. High potassium silage poses a significant risk for milk fever. We can blood test cows 24-48 hours after calving to measure calcium levels and assess herd risk levels.
What I find quite useful is monitoring urine Ph. of close up cows and manging DCAD in 'at risk' herds.
There is no doubt early intervention where hypocalcaemia is an issue will have huge benefits for the overall health of the herd.
Tommy Heffernan runs a veterinary practice in Avondale, Co Wicklow
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