Cows need supplemental magnesium when grazing failed wheat
April 23, 2023
As insurance adjusters tour the area, much of the droughted wheat acreage has been released to producers. Some of these fields have enough standing forage for haying, but most do not. The more efficient method to utilize this standing forage resource is to turn cattle into these fields for grazing. All weights and classes of cattle can benefit from the excellent nutritional value in this forage resource.
If beef producers are utilizing graze-out wheat or rye with lactating beef cows, they should not forget to supply adequate mineral nutrition for these high-producing animals. Grass tetany occurs when circulating magnesium (Mg) is low in the beef animal. Symptoms include staggering, convulsions, excitability, twitching, and can result in death. While it can affect growing cattle, it generally affects older lactating cows.
Many commercial wheat pasture minerals contain Mg as an ingredient in the standard composition. This mineral should be supplied according to label directions to ensure adequate intake. If you are adding Mg to your own loose mineral, you will need to add nine pounds of magnesium oxide per 50 pounds of mineral mix. Sodium deficiency can increase the risk of magnesium deficiency, so if using a mineral fortified supplement that is provided daily, such as cattle cubes (and not a free-choice mineral) make sure that free choice salt is provided. For a salt-based, four oz/day intake mineral, a high magnesium mineral would be considered 10 to 13% Mg.
While providing high Mg mineral helps reduce the incidence of grass tetany, producers should talk to their local veterinarian and have a treatment plan in place for cows who do succumb to grass tetany, as treatment must take place quickly in those cows.