Lush Kentucky pastures may be pleasing to the eye, but painful to grazing cattle, says Ray Smith, University of Kentucky (UK) Extension forage specialist. He warns that legume or frothy bloat is a concern on pastures with prolific white clover growth and slow grass growth this spring.

Frothy bloat is different from gaseous bloat, which happens more when cattle are fed grain. It’s also more difficult to relieve.

“Usually, frothy bloat happens when cattle are grazing forages that are high in soluble protein combined with rapid fermentation,” says Jeff Lehmkuhler, UK Extension beef specialist. “It produces a stable foam in the rumen that blocks the normal escape of the gas from fermentation through eructation or belching.”

The cow’s rumen becomes distended, which causes pressure against the diaphragm and can keep the animal from breathing normally, adds Michelle Bilderback, UK Extension veterinarian. “Wet, lush forages reduce chewing activity and saliva production. Saliva contains mucin, which has been shown to be key in disrupting and preventing the formation of this stable foam,” she says.

Providing palatable, good-quality grass hay to stimulate rumination may help prevent frothy bloat. Some researchers, however, say that may not be enough.

“We commonly use feed additives to prevent and reduce bloat severity,” says Roy Burris, Extension beef specialist for the UK Research and Education Center in Princeton. “Using ionophores has been shown to be effective in preventing and reducing the severity of bloat.”

Poloxalene is a proven bloat-preventing feed additive but can be costly to feed, Lehmkuhler says. Producers commonly use poloxalene blocks, but can also get the additive in powder form to mix with supplements or minerals. During periods of severe bloat risk, the target intake level of poloxalene is 2 grams per 100 lbs of body weight.

“You can reduce it to 1 gram per 100 lbs of body weight as the risk to bloat diminishes.” Recommendations call for adding poloxalene two to three days before putting cattle on pastures at risk to promote bloat. It must be fed daily, he adds.

Producers can contact Burris, Lehmkuhler or a local Extension agent for product recommendations. Most products are readily available from feed dealers who sell free-choice mineral mixtures. Some additives may be helpful but expensive.

Other practical management strategies to reduce frothy bloat exist, says Smith.

“Ideally the legume content of a pasture should be below 50% to reduce the risk of bloat throughout the grazing season. Allowing legumes to mature to late-bud, early bloom stage will also reduce the bloat risk,” he adds.

“Moving cattle to pastures with less legume content and returning to pastures when the legumes have advanced in maturity might be an effective strategy,” Lehmkuhler says. “You do want to avoid moving cattle to new fields with high legume content when they are hungry. Attempt to fulfill their hunger with high-quality hay, if necessary, before moving into legume pastures. Monitor cattle frequently throughout the day.”

If you’re faced with frothy bloat, take quick action and treat promptly, Bilderback stresses.

“Death can occur in as little as one hour after grazing begins but is more commonly seen three to four hours after bloat starts,” she says. “If life-threatening, your veterinarian may do an emergency rumenotomy (cutting a hole in the rumen) to relieve the pressure. If the animal is not in immediate danger, passing a stomach tube into the rumen and administering an antifoaming agent such as mineral oil may aid with the problem.”