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Prevent milk fever by testing calcium levels

Data collected by James Husband of Evidence Based Veterinary Consultancy (EBVC) Penrith, from 15 dairy farms, found more than half of cows had low calcium levels post-calving...

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Milk Fever – prevention is better than cure #TeamDairy

Data collected by James Husband of Evidence Based Veterinary Consultancy (EBVC) Penrith, from 15 dairy farms, found more than half of cows had low calcium levels post-calving. Many of these cows showed no signs and were only detected by blood sampling.

 

Milk fever is the common term used for the signs seen in cattle when blood calcium levels are low, also known as hypocalcaemia. Blood calcium levels are normally kept under tight control by hormonal pathways.

 

Mr Husband says: "At calving however, cows’ requirements for calcium increase dramatically. This is because much more calcium is needed to produce colostrum and milk compared to what is needed for a developing foetus. Although cows’ hormones will adapt to this requirement, it can take a few days.

 

"This means blood calcium levels can be low which result in the signs we recognise as milk fever. Older cows’ hormone responses to the increased requirement for calcium take longer which is why they are more prone to milk fever. As well as being important for bones and teeth, calcium is vital for muscles to work properly. The signs of low calcium are therefore related to muscle weakness. Cows develop muscle tremors, lie down and are unable to rise.

 

The muscles of the gut are affected, leading to a slow down in gut movements, bloat and constipation. Left untreated, if the muscles that assist breathing fail, cattle can die.

 

"In some herds calcium levels are lower than they should be around calving without downer cows being seen. Blood sampling could reveal a problem and allow you to make adjustments to improve the health of the herd."

 

 

Milk fever is the common term used for the signs seen in cattle when blood calcium levels are low, also known as hypocalcaemia. Blood calcium levels are normally kept under tight control by hormonal pathways.

 

Mr Husband says: "At calving however, cows’ requirements for calcium increase dramatically. This is because much more calcium is needed to produce colostrum and milk compared to what is needed for a developing foetus. Although cows’ hormones will adapt to this requirement, it can take a few days.

 

"This means blood calcium levels can be low which result in the signs we recognise as milk fever. Older cows’ hormone responses to the increased requirement for calcium take longer which is why they are more prone to milk fever. As well as being important for bones and teeth, calcium is vital for muscles to work properly. The signs of low calcium are therefore related to muscle weakness. Cows develop muscle tremors, lie down and are unable to rise. The muscles of the gut are affected, leading to a slow down in gut movements, bloat and constipation. Left untreated, if the muscles that assist breathing fail, cattle can die.

 

"In some herds calcium levels are lower than they should be around calving without downer cows being seen. Blood sampling could reveal a problem and allow you to make adjustments to improve the health of the herd."

 

The uterus is a muscle which requires calcium to work properly. Low calcium levels can stop labour from progressing normally resulting in increased numbers of stillbirths. Low calcium levels also increase the risk of cows having retained placentae. This increases the incidence of endometritis and metritis which has a detrimental effect on fertility. The stomach is also a muscle and it is recognised that low calcium levels predispose to the stomach, or abomasum, becoming displaced.

 

Mr Husband says: "In order to manage anything it is important to be able to measure it. Measuring the incidence of different conditions that occur around calving time may give an indication if further investigation is warranted. Testing calcium levels would form part of this work up. Both target and interference levels should be discussed with your vet and a farm specific plan agreed. Conditions that should be monitored include number of downer cows, retained placentae, endometritis, metritis, stillbirths and displaced abomasums."

 

Milk fever is treated by a vet by giving 400mls of a 40 per cent calcium solution slowly into the vein. It is, however, better to prevent the condition, says Mr Husband.

  • Ensure cows calve in the correct condition score (2.5-3.0). Cows that are over fit at calving have reduced dry matter intakes predisposing to hypocalcaemia.
  • Ensure dry matter intake is optimal by ensuring diet is palatable and feed trough space is sufficient to ensure ad-lib access.
  • Limit the amount of calcium and potassium in the dry cow diet. This can be difficult on grass based forage systems. Forages can be tested to assess these macro-mineral levels. It should be remembered that fields that have had slurry applied will produce high potassium forage. Dry cow forages diets could therefore be made from fields that have not had slurry applied.
  • Ensure sufficient magnesium is supplied in the dry cow diet.
  • Discuss control and prevention of milk fever with your vet and nutritionist.

Blood calcium levels

  • Blood calcium levels should be above 2 mmol/litre.
  • When they drop to less than 1 mmol/litre cows become recumbent.
  • Cows with calcium values between 1 and 2 mmol/litre will not show typical clinical signs of milk fever but they are predisposed to other conditions.
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