Why Use HI-MAG Mineral?

— Written By and last updated by Deb Fuller
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Using a HI-MAG mineral in the spring is something all of our cattle producers have heard for years and many of us pay that extra cost to put that mineral supplement out. But do we really know why we are putting this mineral out?

The main reason we use HI-MAG mineral is to prevent grass tetany in our cattle. Grass tetany is a condition where there is an inhibited or insufficient supply of magnesium available to the cattle in their feed. This is a much more prevalent issue in high quality forages which may contain excessive levels of potassium that inhibit magnesium uptake. This happens more often in lactating cattle and growing calves’ more than dry cows or bulls. Grass tetany affects the nervous system and causes the cattle to become lethargic, have staggers, excessive drooling, and in extreme cases death.

Our recommendation is that these supplements be consumed at 4 oz/animal unit/day, and should contain 10-14% magnesium, .09% copper from copper sulfate (.13% copper for Simmental and other exotic breeds), .18% zinc and .0026% selenium. A lower cost (low phosphorus) high magnesium supplement can be used if phosphorus is known to be adequate. Also, molasses/magnesium blocks are available for use on farms with a high incidence of grass tetany.

The issue with HI-MAG mineral is that it is very bitter and producers have a hard time getting cattle to consume the recommended rates. One way to offset this is to feed HI-MAG mineral year-round so that the cattle get accustomed to the taste of the mineral. Although with the extra cost of the mineral and still decreased intake that is not my favorite method. Another option is to start putting out HI-MAG mineral 2-3 months before spring grass flush and pulling their salt block or loose salt. This method forces the cattle to get used to the mineral and they will actually seek it out for the salt in the mineral. After spring flush of grass we can switch those cattle back onto our normal mineral and add the salt back as well.

The most prevalent issues we see with grass tetany is in pastures that are heavily fertilized with chicken litter or inorganic fertilizers. This increases the yields as well as the nutritive content of the grass and causes the excess potassium that inhibits uptake of magnesium. This is not a play to stop people from heavily fertilizing their pastures but please consider adding HI-MAG mineral into your program so that any issues can be prevented. I also want to add that for those producers who have never had issues with grass tetany that it is still not a bad idea to use a HI-MAG mineral in the spring as to prevent any issues form arising.

If you have questions about HI-MAG or any other livestock issue, contact Livestock Agent Cole Maness at 336.641.2413 or scmaness@ncsu.edu