Addressing milk fever in your organic dairy herd

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One of your best cows calved a couple of days ago and now she's down, lying on her sternum, head lying along her side with a kink in her neck. Her eyes are glazed over, pupils dilated and she can't get up. If observed earlier she may have been off feed and exhibiting muscle tremors and unsteady gait. This is an easy diagnosis for most dairy farmers to make ... milk fever, parturient paresis (calving paralysis) or hypocalcemia (hypo- or low) calcemia (calcium).

Whatever term you use, if untreated, this condition can result in death in a few hours.

I believe that almost all dairy cows suffer from some degree of low blood calcium at calving time. Most are subclinical (not showing symptoms) in nature and do not show the classical signs described above. Calcium is necessary for all muscle function. Even moderately low blood calcium can set cows up for calving problems, retained placentas, uterine prolapse (cast withers), and reduced reproductive performance as well as digestive and metabolic disorders such as displaced abomasums and ketosis. Low blood calcium affects the immune response and may be a factor in mastitis, metritis and other infections.

Incidence of this condition may vary from 3% to as high as 30% in some herds. Estimated profit loss from lost production, death loss, and veterinary costs associated with clinical cases of milk fever range as high as $225 for each episode. The losses from subclinical milk fever may be substantial but are more difficult to measure. Some old-timers say that if a cow "yawns" when you pinch her withers, it indicates low blood calcium. Hmmm?

Treatment Options

The standard treatment for this emergency is calcium borogluconate. It may be administered intravenously (in the vein), subcutaneously (under the skin), or intraperitoneally. If the animal does not respond, a solution containing magnesium and phosphorus along with calcium may be necessary. In early cases or as a preventative in high risk cows, liquid calcium or calcium chloride gels given orally may be beneficial. (Always check with your certifier.)

Different authorities cite different causes for milk fever. In the past, excess calcium was considered the culprit and limiting calcium levels in the dry cow ration was the standard recommendation. Some blame the high potassium in legumes and some grasses caused by inappropriate fertilizer practices. Low calcium, high calcium, high potassium, low phosphorus, low or high Vitamin D, low magnesium, reduced mineral adsorption if rumen pH is over 6.8 to 7.2 , water pH over 8.5 have all been implicated at one time or another. I guess you can just take your pick. In truth, all these factors play a part and the common denominator is a "mineral imbalance." While mineral balance is important to animal health at any time, it is especially critical for the dairy cow at calving time.

During the dry cow period and especially in the last three weeks before calving, if the Ca/P ration is 1:1 or even higher in Ca, there is a relative deficiency of phosphorus. To compensate for this, the body sets up to reject calcium and to absorb phosphorus. After calving, it takes 72 hours for the metabolism to readjust to absorb adequate amounts of calcium.

As the cow approaches calving, large amounts of calcium are drained from the blood reserve to form colostrum (high in calcium) and to begin milk production. At calving, the sudden increased demand for calcium by the mammary gland uses up blood calcium faster than it can be replenished from other body reserves and thus sets the stage for hypocalcemia.

Prevention Strategies

The key to prevention of milk fever is management of the close-up dry cow.

All health begins in the soil. Strive for crops grown on highly mineralized, high organic matter soils that are free from residues of insecticides, herbicides and GMO sources.

Feed a high forage-low grain ration. A cow is a ruminant; don't feed her like a hog. Avoid alfalfa and other feeds or forages that are high in calcium and potassium.

Feed an enzyme product with good levels of phytase to release the naturally chelated minerals already present in your feeds. Minerals thus released from the digestion of feeds and forages are much more available than minerals from ground-up rocks added to the ration. This not only benefits the health of your animals but also saves money by the more efficient utilization of home grown feedstuffs.

In addition to any minerals found in or added to the ration, allow your animals to adjust their own individual mineral needs by providing separately and free-choice, a highly available source of phosphorus (monosodium phosphate) along with separate sources of calcium, magnesium, potassium and trace minerals. Dicalcium phosphate is not suitable for this purpose because of its high ratio of calcium to phosphorus. Monosodium phosphate is preferable because of its higher availability but it is the most expensive source and not generally used in the feed industry. The quality of ingredients used can vary greatly. Check labels; all minerals are not the same. Organically certified commercial products that meet these criteria are available.

Milk fever is not a disease but only the clinical expression of a mineral imbalance at a period of physiological stress. While the final expression of milk fever is caused by low blood calcium, a predisposing cause can be either low phosphorus in the ration or sources of phosphorus that are relatively unavailable. What an animal actually absorbs into its system is the only thing that counts.

Remember: it's all about internal mineral balance!

Disclaimer

The information provided herein is for educational purposes only. The author and publisher have no control over the use, misuse of applicability of this information to your situation and thus assume no liability. Always consult your veterinarian or other licensed health professional before making any changes in animal health management. If applicable, always obtain prior approval from your organic certifier before using any products or procedures discussed or recommended on this site.

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

© eXtension 2008.

www.extension.org/article/21674

The article is provided under a limited license from eXtension.org.



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