Bloat at pasture turn-out – recognize the risks

Grazing legumes increases bloat risk for cattle and sheep.

Bloat, or frothy bloat, is a life-threatening disease in cattle that can occur when animals ingest young, vegetative legumes. The most common bloat causing legumes grazed in Michigan are white clover, alfalfa and red clover. Grazing legumes shorter than ten inches in height will double the risk of bloat.

Forages are about three weeks ahead of schedule due to the warm temperatures. Grazers are watching those pastures closely gauging when to begin grazing.  Legumes, which are high in soluble protein, can cause the formation of a froth that traps gasses in the rumen. Being unable to expel gas can cause the animal’s rumen to distend. As pressure increases, breathing is affected, which can lead to death from suffocation. Cattle and sheep can die from bloat in as quickly as an hour after grazing begins, but more commonly, death occurs after 12-48 hours of grazing on a bloat-producing pasture.

The main symptom of bloat is a swollen left abdomen. Other symptoms include repetitive standing up and lying down, kicking at the belly, frequent defecation and urination, grunting and extension of the neck and head. If untreated, the animal will collapse and die within three to four hours after symptoms appear. Quick intervention is the key to saving affected animals. Treatment can range from orally tubing the affected animals to emergency intervention of a trocar that punctures the rumen behind the ribs and below the loin to immediately release rumen gas pressure.

Reduce the risk of bloat by following these management practices:

  • Establish grass-legume mixtures instead of pure legumes (60% grass and 40% legume is desirable)
  • Avoid grazing immature legumes
  • Watch animals closely after frost or a significant change in the weather
  • Avoid grazing frost damaged legumes for seven days after the frost event
  • Do not put animals into legume-rich pastures when the pastures have moisture on them from rain or dew
  • Make certain livestock are full of dry hay before turn-out to prevent overconsumption
  • Do not remove animals from a pasture when bloat symptoms first appear. Continuing grazing causes less incidences of bloat as the cattle consume higher fiber portions of the plant
  • Feed bloat-reducing compounds like poloxalene in block-form 24 hours prior to turn-out and in the high risk pastures
  • Give animals access to water and minerals
  • Cull animals that have frequent bloat problems

For additional cattle management resources, visit the MSU Beef Team website at

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