PHOTO: Matt Barton, UK agricultural communications specialist With spring finally arriving pastures are beginning to green up. For most cattle producers, that is a welcome event that leads to less reliance on feeding hay. But University of Kentucky College of Agriculture, Food and Environment specialists said this is also the time for producers to watch out for and prevent a condition called grass tetany in their cattle.
“Grass tetany is also known as grass staggers, lactation tetany or hypomagnesemia,” said Michelle Arnold, UK extension veterinarian. “Grass tetany is a metabolic disorder caused by reduced magnesium levels in the animals’ blood.”
In general, the condition affects older, early lactation cows, but it can also affect dry cows, young cows and, in rare cases, growing calves.
“You should watch out for cattle that show symptoms such as nervousness, lack of coordination, muscle spasms and staggering. This may lead to convulsions, coma and death,” Arnold explained. “If you suspect cattle are showing signs of grass tetany, you need to contact a veterinarian because early treatment can save animals.”
While grass tetany can occur in fall and winter, it most frequently occurs in spring with young, cool-season grasses and small grains that are utilized as forage.
“This year we have the same chance of cattle having problems with grass tetany as in previous years,” said Donna Amaral-Phillips, UK dairy specialist. “With the later start in grass growth this year, grass tetany may occur later in the spring, but a lot of it comes down to the weather as we proceed.”
While there may not be a higher incidence of the problem this year, managing it may be more economically significant than past years.
“The high-value of beef cattle this year makes managing the risk of grass tetany even more important from an economics point of view,” said Jeff Lehmkuhler, UK beef specialist. “Cull cows are currently in excess of $100 per hundredweight and feeders are around $1,000 to $1,200 per head. So, minimizing the risk is relatively inexpensive and definitely worth the cost.”
Feeding magnesium or “high-mag” mineral supplements is the best way to reduce the occurrence of grass tetany. Most feed stores carry the supplements. Ideally producers need to start feeding those supplements 30 days before spring grass growth. A free-choice high mag mineral, with a target intake of 4 ounces, should contain 12 to 15 percent magnesium from magnesium oxide.