Dairy Event 2011: Calculating the cost of milk fever

Subclinical milk fever could be costing producers as much as 1ppl with the cost of a clinical case running into hundred of pounds.

Speaking at a Farm Health Planning seminar at the Dairy Event and Livestock Show, vet Richard Cooper from Evidence Based Veterinary Consultancy said milk fever was a gateway disease to a host of other disease issues.

“Milk fever opens the door to cows crashing post-calving. A cow with clinical milk fever will be nine times more likely to get ketosis, eight times more likely to develop mastitis and four times more likely to have retained foetal membrane.”

Mr Cooper put the direct cost of a case of clinical milk fever at £65, with indirect costs from reduced fertility and a greater likelihood of culling, at £200-300 a case.

“Even sub-clinical milk fever could be costing dairy producers up to 1p/litre and for every one clinical case there are potentially three to six subclinical cases below the surface,” he said.

During the transition period a cow’s calcium needs increase dramatically. Parathyroid hormone release when an animal is low in calcium enables the cow to draw on bone stores. At the same time an increase in Vitamin D3 in the kidneys means less calcium is lost in the urine, helping to restore levels.

Magnesium is very important in helping to prevent milk fever, Mr Cooper continued. “Potassium will decrease magnesium so the name of the game is to increase magnesium intake to reduce the blocking effect of potassium.”

Mr Cooper said there were a number of ways to prevent milk fever from occurring.

“You can ‘starve’ dry cows of calcium – in this way they will gear up their survival mechanism so they are ready to go at calving.”

Adopting a DCAB system that aimed to create metabolic acidodis would also result in a cow buffering the blood with calcium carbonate from the bones. However he recognised that a full DCAB system was complicated and “put cows on a very high tightrope”.

“A partial DCAB system is best for most. The key is to minimise the amount of high potassium forages produced – keep slurry and potassium fertiliser applications to a minimum on dry cow fields and keep grazing short.”

Prompt treatment of clinical cases, or at-risk cows, such as older animals or individuals that have had a tough time, was also important.

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