Milk Fever

     Each incident of milk fever in dairy cows is estimated to cost the dairyman about $335.00. This figure does not include the cost of subclinical hypocalcemia, or  other often associated conditions such as dystocia, retained placenta, metritis, and displaced abomasum.  Milk Fever or peri-parturient hypocalcemia is caused by failure to maintain adequate levels of blood calcium at calving time.

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      Several recent internet articles dealt with strategies to lower the incidence of  milk fever in dairy cows.  All were written by University folks and all contained pertinent information. They all recommended the same old standard fixes: feed pre-fresh cows low calcium and low phosphorus rations and forages (limit pre-fresh cows to no more than 20 g/day of calcium and 80 g/day of phosphorus), feed anionic salts for 21 days before calving, and  treat affected cows as soon as any symptoms are noticed. 

     The common thread seems to be  to  micro-manage the mineral consumption of all animals to conform to commonly accepted parameters.  Given the variability of forages and feeds this may be difficult to implement on many farms.  One writer warned against allowing cows “selective consumption” of forages and advised to discontinue free-choice mineral feeding and to force feed all minerals.  This mind set disregards individual variation of needs. If all minerals are force fed in a TMR, some cows get too much, some get too little, and only a few get what they need.

     One author did point out that high levels of calcium and potassium in the blood caused the  'bone to blood pathways' of calcium mobilization to shut down.  After calving, it takes about 72 hours to reestablish this process—during which time the fresh cow is prone to milk fever. 

      I was disappointed no one mentioned the role of maintaining a proper dietary calcium/phosphorus ratio in the last three weeks of pregnancy.  Mineral balance is oft times more important than absolute amounts.

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      The ‘keystone concept’ they all missed is this. If dairy cows have free-choice access to separate calcium and phosphorus sources, they will self-adjust their individual Ca/P ratios and not disrupt the calcium mobilization pathway mentioned above.  When they calve they are less susceptible to milk fever.  

     I guess until dairymen, and nutritionists, discover the nutritional wisdom of cows  they will have to accept the current incidence of  milk fever—estimated to be 25 percent calving with clinical milk fever and another 25 percent calving with sub-clinical milk fever.

You might want to check out my article, “Addressing Milk Fever in Your Organic Dairy Herd.” —originally published in  Holistic Veterinary Practice  Dairy Herd Network   July 30, 2009.    

It can be viewed at:   http://www.dochollidaysblog.com/article-index/milk-fever.html

rjhdvm@gmail.com