Keep Livestock Healthy When Turning Out to Pasture

A country vet answers questions about putting livestock out to pasture, including preventing grass tetany in cattle, grass founder in ponies, and the truth about buttercup poisoning.


| April/May 1992



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Anyone who owns livestock should have a thermometer and a speaking relationship with a local veterinarian.


PHOTO RESEARCHERS/ELIZABETH WEILAND

A few years ago I realized a lifelong dream in Switzerland—I watched the cows trek from the valley stables to the mountain pastures. The big brown cows wore flowers around their necks and on their heads. They strode rapidly along the autobahns and through the village streets, cowbells chiming. The lead cow, wearing the largest flower arrangement and most decorative strapped bell, needed no one to guide her. She knew she was heading for green grass.

Seeing cows go to pasture always lifts my spirits after a long winter. I don't know whether it's due to my childhood experience or my Swiss ancestry. During my early years of practice, we were sometimes plagued in March with sick cattle, which would not respond until we could get them out on grass. I used to count the evenings when the beautiful sound of spring peepers would be heard. After hearing the frogs three or four times, I knew there would be enough grass on the south side of some hill, where a sick cow could be turned.

Today we have better knowledge of harvesting roughage and feeding/caring for cattle. We don't experience problems with acetonemia, displaced abomasum, and slow recovery of sick animals which plagued us 40 years ago. I now read of dairy farmers who return to pasture management from the extreme of zero pasture. But the magic of green grass is not always the answer—sometimes it causes problems. From the questions that MOTHER receives, it is clear that not all of our readers are able to avoid late winter health problems with their livestock. Let's address a few questions:

Prevent Grass Tetany

Q. Early last spring, we turned our family Jersey cow and our small beef herd of Hereford out onto winter wheat before the grass pasture was ready. Two days later the milk cow went down and into a coma, as if she had milk fever. I called our veterinarian, who saved her life with intravenous calcium and magnesium treatment. She said the cow did not have milk fever, but a similar disease called "grass tetany," which is caused by too little magnesium. She also said that the beef cattle could get the disease. At her suggestion, we pulled them off the wheat and turned them to the grass pasture, supplemented with some hay. The veterinarian also told me it was possible to prevent grass tetany by fertilizing with magnesium, but one could never be entirely sure. We'd like to be able to pasture wheat again this year. Is there a safe way to do it? 

A. There are so many factors known and unknown about grass tetany that one can never be sure about prevention or treatment. It affects cattle and sheep, usually those in heavy lactation. It is known even in steers, and can be fatal if not detected in time. Most importantly, it is seen in cattle raised on highly fertilized pasture, particularly where a lot of nitrogen is used. Wheat pasture is most apt to cause it, but I have seen it on wild unfertilized pasture during cold, wet springs. Stress—such as too many hours without feed—is another contributing factor. Cows prone to milk fever, such as your Jersey, are also more prone.

To prevent grass tetany, spray pasture with a 2% magnesium sulfate solution (epsom salts, 2 pounds to 12 1/2 gallons of water) just before turning animals out. Liming with high magnesium lime during the fall is another solution. Remember that young, fast-growing green plants are low on magnesium.





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