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Preventing bloat in livestock

PINE BLUFF, Ark. – Bloat can kill ruminant animals quickly, sometimes in as little as an hour, says Dr. David Fernandez, Cooperative Extension Program livestock specialist at the University of Arkansas at Pine Bluff. Often the only sign of bloat is a dead animal in the pasture.

Bloat is common when cattle are on lush pastures or eating grain to boost gain. Gasses trapped in the rumen press against the diaphragm, and the animal cannot breathe.

“There are several types of bloat, but most have one thing in common – foam,” says Dr. Fernandez. Methane and hydrogen gases are normal byproducts of fermentation in the rumen. Normally, the gas accumulates above the feed and fluids in the rumen and exits when the animal burps. Under certain conditions, proteins from plants can form tiny bubbles around these gases and trap them in the rumen.

“You can usually see this as swelling on the left side of the animal. If you tap firmly on the swelling, it will sound like a drum,” he says.

Pasture bloat is probably the most common. Livestock grazing pastures with lots of high protein forages like legumes and clover are more likely to suffer from bloat. Some high protein forages such as sainfoin, crown vetch, milk vetch, fenugreek and birdsfoot trefoil are also high in condensed tannins. They reduce the potential for bloat by binding other proteins and slowing the rate of digestion. Young grain crops and brassicas, such as turnips and rape, can also contribute to bloat.

Grain bloat seems to be caused by a slim-producing bacterium that thrives on high carbohydrate diets and lower pH. The combination of bacterial slime, lower pH and small particle size of grain diets, especially ground corn, creates foam leading to bloat.

Bloating in the abomasum, one of the components of a ruminant digestive system, is usually seen in young, bottle-fed livestock less than three weeks old. Infrequent feedings of cool milk that can be consumed rapidly contribute to abomasal bloat. Kids, calves or lambs overeat at these infrequent feedings. Animals grind their teeth and salivate, appear depressed and refuse to eat. The abomasum swells, and “tinkling” or splashing can be heard if the animal is shaken. Treatment outcomes are usually poor.

The exception is when something blocks the esophagus. The animal may have swallowed an apple, potato or something that has lodged in the esophagus and prevents gas from escaping. Animals trapped on their back or side can become bloated when the rumen contents block the esophagus. 

“Quickly dislodge the obstruction,” advises Dr. Fernandez. “Stand clear of the mouth when you do as the gas can escape suddenly and bring some rumen contents with it.”

Mineral or vegetable oil can reduce the surface tension of the foam and allow gas to escape. Dosage for cattle is a pint to a quart. Liquid soaps are also effective. A few ounces of dishwashing soap in water will break down the foam and allow gas to escape, says Dr. Fernandez. Several over-the-counter products are essentially combinations of detergents and do the same thing.

Old-timers used a bloat needle or even a knife to puncture the rumen and allow gas to escape, but this is dangerous and should only be done if the animal’s life is in immediate danger. The risk of infection and peritonitis is too high to undertake this step lightly, says Dr. Fernandez.

Bloat can be prevented by including ionophores such as lasalocid or monensin to the diet. Be sure to check the label for approved uses and species. “Lasalocid is toxic to horses,” warns Dr. Fernandez.

Maintain adequate roughage in the diets of animals on high grain diets. Introduce livestock gradually to pasture containing high levels of bloat-promoting forages. Feed grass hay before allowing them to graze for an hour or so gradually increasing grazing time and reducing hay feeding. Increase grass in legume pastures and watch your animals.

For more on bloat or other livestock questions, contact, Dr. Fernandez at (870) 575-7214 or


By Carol Sanders, writer/editor
UAPB School of Agriculture, Fisheries and Human Sciences
(870) 575-7238

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