Young green grass carries risk of tetany in cattle

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This year has started unusually warm and wet. So much so that grass is beginning to green early than past seasons. With young green grass it is thought to be an advantage but it also carries the risk of grass tetany for cow/calf producers.
Early spring is the primary time that farmers experience problems and loss of livestock to the forage related disorder known as grass tetany, grass staggers, lactation tetany, or hypomagnesemia. Grass tetany is a metabolic disorder caused by reduced magnesium (Mg) levels in the animal’s blood. High levels of Nitrogen (N) and Potassium (K) in the soil can increase the risk of grass tetany. It generally effects older, lactating cows but is also seen in dry cows, young cows, and, in rare cases, growing calves. Young cool season grasses and small grains are commonly associated with this disorder. Grass tetany is most frequent in the spring but may occur in the fall and winter when these forages start growing rapidly or when cereal grain forages are fed.
Symptoms may consist of nervousness, lack of coordination, muscular spasms, staggering, convulsions, coma, and death. If there is a suspicion of grass tetany, a veterinarian should be called immediately.
Feeding high magnesium or high “Mag” mineral supplements, containing magnesium oxide, is the preferred method to reduce the occurrence of grass tetany. High “Mag” mineral mixes are available at most feed stores. Producers can also mix their own by adding the appropriate amount of magnesium oxide to another supplement or feed where the intake is controlled, i.e. feeding in or with one to two pounds of corn or other byproduct. Livestock should be fed this supplement starting in December or January and continued until spring time when temperatures are consistently above 60°F. To provide adequate amounts, 20 g of magnesium must be provided and consumed daily. Free choice minerals should contain 12 to 15 percent magnesium (from magnesium oxide) and cattle need to consume four ounces of the mineral. It is important to monitor intake to be sure cattle are consuming adequate amounts each day to provide protection against grass tetany. Lactation doubles Mg need and early plants do not take up Mg fast enough to provide adequate amounts.
The season for grass tetany is around the corner. To reduce health problems and loss of livestock to this disease, it is important to provide a quality, “high Mag” mineral or magnesium oxide containing supplement. Ask your county agent, veterinarian, or nutritionist for more information on supplementing Mg during periods of high risk.
Article provide by: UK Grazing News January 2012 Newsletter