SCIENCE …
OR THE NITTY
GRITTY STUFF!

 
 
 
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 SCIENCE …
OR THE NITTY
GRITTY STUFF!

 
 
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 WHAT IS MILK FEVER

 
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Hypocalcaemia and milk fever occur when cows do not remove enough calcium from their bones and the diet to meet the demand for calcium lost in milk. Instead they draw the calcium from the muscles and nerves leading to muscle weakness or ‘downer cows’. This can occur at any stage during the lactation.

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The two biggest impacts of milk fever are decreased muscle function and depressed immune function.

Cows with milk fever are also:

  • 8x more likely to develop mastitis

  • 3 – 6x more likely to endure calving difficulties

  • 3x more likely to experience retained foetal membranes (RFM)

  • 2 – 5x times more likely to develop displaced abomasum.

The average incidence of milk fever across New Zealand is 2%. On individual farms the incidence of milk fever can be as great as 30%. For every one clinical milk fever case as many as 10 cows could have sub clinical hypocalcaemia.

Clinical Case
In a clinical case impaired nerve and muscle function leads to the ‘downer cow’ situation.

Sub Clinical Case
In a sub clinical case the muscles of the digestive tract, uterus and teat end may be impaired.

Reduced rumen and gut motility lead to reduced dry matter intake. Decreased dry matter intake results in a reduction of energy intake and rumen fill leading to increased risk of other metabolic disorders such as ketosis, fatty liver and displaced abomasum.

Milk Fever or sub clinical hypocalcaemia can also

  • lead to decreased energy intake – negatively impacting the milk yield

  • effects the uterus and could result in calving difficulties or prolapse.

  • could ultimately lead to decreasing reproductive performance, due to milk fever impacting the uterus

  • result in mastitis due to a reduced immune function.

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SIGNS & STAGES OF MILK FEVER

Typically, acute milk fever occurs within a few days after calving. If milk fever occurs within the first 48 hours after calving, it is an indication that the Close Up Dry Cow programme was not adequate. If milk fevers occur within 10 days of calving, the colostrum group did not get enough calcium supplementation. If milk fevers occur at a later stage during the lactation (i.e. autumn milk fever) it is a strong indicator that calcium supplementation is inadequate.

Sub-acute milk fever cows experience muscle twitching and tremors; the cows are excitable. In these cases there is often a magnesium deficiency as well. In all cases ensure adequate calcium and magnesium is supplied to the cow.

Refractory milk fever is an acute form with poor or no response to treatment. This cow may remain alert, eat and milk but cannot get up. The best way to mitigate problems associated with milk fever is prevention through a sound Close Up Dry Cow program and adequate supplementation of calcium through the entire season.

 
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THE IMPORTANCE OF CALCIUM

Read more in depth information about the importance of calcium during the lactation.

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