In my neck of the woods, we are months away from having any green grass for grazing, but for areas with warmer spring temperatures, the grazing season is just beginning and along with it, concerns such as grass tetany.
In a recent article for the Ohio State University Extension Beef Newsletter, Michelle Arnold, DVM, University of Kentucky ruminant veterinarian, offers five tips for preventing and treating grass tetany in cattle this spring:
1. Consider a high magnesium mineral mix instead of plain salt
Arnold writes, “For those few lucky producers, the minerals available in their soils and forages are enough to meet the needs of their cows. A number of complex factors contribute to the ability of magnesium to be absorbed through the rumen (stomach) wall. Primarily there is a ‘pump’ mechanism that actively transports the dissolved form of Mg across the rumen wall to the bloodstream. This pump doesn’t work when potassium in the rumen is high and sodium is low because this changes the electrical potential necessary to drive it.
“Adding salt to the ration will improve Mg transport only when sodium is low in the overall diet. Too much salt will increase urination and cause magnesium to be lost in urine. Salt, as with any substance, can be dangerous and even fatal at high levels. Research has shown that the negative effects of high potassium in early spring grass cannot be overcome by the addition of large quantities of salt. However, high magnesium mineral mixes prevent grass tetany by allowing magnesium to passively flow into the bloodstream of the cow without the need for the active transport pump.”
2. Begin supplementation 30 days prior to calving
“Supplementation with high magnesium mineral should begin at least 30 days prior to calving,” says Arnold. “Cows require 20 grams of magnesium daily or 4 oz. per day of a 15% magnesium mineral mix during the late winter and early spring. Mineral feeders should not be allowed to be empty because consistent intake is important for clinical disease prevention.”
3. Soil test
Arnold suggests, “Soil test and apply fertilizer based on soil test results and use no more potassium than recommended since grasses are luxury consumers of potassium.”
4. Feed some hay to cattle on pasture
“Feed small amounts of hay and/or grain to cattle on lush pasture during susceptible periods or limit grazing to 2-3 hours per day,” says Arnold.
5. Determine which animals are at greatest risk
“Graze the less susceptible or non-lactating animals (heifers, dry cows, stocker cattle) on the higher risk pastures,” she advises.
Arnold concludes, “Increasing magnesium intake by supplementing with magnesium oxide, offering adequate salt to prevent sodium deficiency, and increasing total energy intake with good quality forage or supplemental feed are all effective tools in preventing grass tetany. These are exceptionally important when moving from winter rations to young spring grass pasture, especially in heavily milking cows. Grass tetany is considered a true veterinary emergency requiring prompt treatment with magnesium to prevent death.”
The opinions of Amanda Radke are not necessarily those of beefmagazine.com or Penton Agriculture.
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