February 2016
Feeding Facts

It’s That Time of Year

Wow, who can believe the weather we experienced in the winter of 2015? Mild temperatures have been a blessing that allowed cattlemen to feed less feed and provided unusual forage growth. The abundant rains have also been great for forage growth, but the excess rain has been devastating to many families with flooding.

We sincerely hope those who have been adversely affected by the Christmas floods and high winds are on their way to getting their lives put back together. We also hope the New Year will bless all of these victims enough that their lives will find prosperity.

Even before the excessive rains came, cattlemen were experiencing production problems of their own. The unusually wet, cloudy and mild weather increased forage growth and we saw problems we usually only experience during the late winter and spring. Many producers started seeing cases of grass tetany in their cattle.

Grass tetany is a result of magnesium deficiency. Magnesium is a mineral necessary for proper muscle and nerve function. Magnesium isn’t stored in their bodies to the degree that calcium and phosphorous are stored; therefore, it must be supplied in their diet.

Normally, there is an adequate amount of magnesium in forage to supply the needs of beef cattle. However, in wet, cloudy weather, a plant’s ability to absorb magnesium from the soil is limited. Because the plant can’t absorb magnesium, cattle consuming this forage become magnesium deficient. The symptoms vary, but include nervousness, excessive salivation, muscle spasms and eventually going down; at that point, they won’t survive long without an IV containing magnesium.

Since we have had and are experiencing problems with grass tetany, we have to determine how we are going to deal with the problem. Cattle need to consume about 0.6 ounces of magnesium daily or about 1 ounce of magnesium oxide daily. There are several ways to supply this amount of magnesium.

The first and most common method is to supply a mineral with higher-than-normal magnesium concentrations. These minerals need to contain at least 12 percent magnesium. Most minerals are formulated for 4-ounce per day consumption and, if the mineral is 12 percent magnesium, this would supply 0.48 ounces of magnesium, which would be borderline in providing enough magnesium to alleviate the problem. The issue with supplementing magnesium in a mineral supplement is consumption. Magnesium oxide isn’t very palatable. So, if you are supplementing magnesium, pay close attention to consumption to insure enough magnesium is being supplied to your cattle.

Supplemental feeds also help to supply magnesium. Feeds containing grain byproducts and fortified with minerals and vitamins tend to help meet cattle’s magnesium requirements. Specialized supplements such as a hot mix are generally fortified with additional magnesium to help with tetany problems. Also, supplements such as our Brood Cow Supplement can go a long way to decrease the incidence of grass tetany.

Another option is to supplement with molasses tubs, especially ones with added magnesium. An advantage of supplying magnesium by this method is enhanced palatability. Cattle will tend to consume this product more readily simply because it is incorporated with molasses. However, it is very difficult to monitor consumption with these products.

Many times, if cattle are consuming good quality hay, producers will not experience problems with grass tetany. Hay from well-fertilized fields usually helps supply magnesium needs. The extra dry-matter consumption will supply some of the needed magnesium. This hay will have to be high quality and palatable to lure cattle away from lush grass, but will sometimes work.

Of all the methods we have examined, my preference is all of the above. When grass tetany is a possible problem, I prefer to give the cattle several options to increase their magnesium consumption. Cattle most afflicted with this problem tend to be cows nursing young calves. Since these cattle are in a highly productive stage of production with many nutritional demands, they would do well on lush grass with some supplemental feed, hay and a mineral containing at least 4 percent magnesium. These are all the most palatable sources of magnesium and insure the greatest success in getting magnesium into your cattle.

As we move into the new year, I wish everyone much success. I hope your year is both peaceful and successful. I hope your operations flourish and, if there are issues, I hope we can help.

Stephen Donaldson is AFC’s animal nutritionist. If I can help any of you, please get in touch with me and let’s succeed together. You can reach me at 256-476-5272 or This email address is being protected from spambots. You need JavaScript enabled to view it..