“Wheat-pasture bloat sometimes called Sudden Death Syndrome is a frustrating problem, often killing the faster-growing calves that consume a greater amount of forage,” says Greg Highfill, Oklahoma State University (OSU) Extension livestock specialist.
According to Highfill, several factors related to plant growth and composition, as well as animal consumption, play a role. As the wheat plants break winter dormancy, the proportion of forage components during this rapid growth phase can contribute to the rumen digestion, producing a frothy foam. With rapid fermentation and conditions to produce a froth covering in the rumen, fermentation gas is trapped and bloat occurs.
“Numerous factors can contribute to bloat conditions specific to each season,” Highfill explains. “In some years, the major culprit can often be cattle engorgement or simply eating too much wheat forage too fast.”
Death usually trails engorgement 9-24 hours. In addition, weather fronts often disrupt normal cattle-feeding patterns. Cattle often consume more forage when a weather change is imminent. The number of bloating cattle can increase rapidly in a few short days.
“One logical management strategy that should help reduce frothy bloat would be to take steps to make wheat-forage intake more uniform and prevent engorgement,” Highfill says.
For instance, Highfill says providing cattle with a feed supplement that contains monensin can be an effective option. Monensin has proven to be effective in reducing the incidence of bloat and should reduce forage intake as well.
“Stocker cattle should receive 150-200 milligrams/head/day of monensin to effectively reduce bloat,” Highfill says. “Purchasing a supplemental feed with the targeted monensin dose and getting it into the cattle are the primary management challenges.” He adds that mineral mixes containing monensin also are available, but consumption typically will vary more from calf to calf.
“Herd managers should assess the bloat risk in their operation to determine the level of protection needed, and possibly consult with their local veterinarian, if appropriate,” Highfill says.
Poloxalene is the generally recommended treatment for significant bloat outbreaks, although it is an expensive feed additive, Highfill explains. While poloxalene reduces rumen frothiness, it must be consumed daily as it has no residual effects in the rumen.
According to Highfill, the generally recommended rate of poloxalene is 1-2 grams/cwt. of bodyweight. The most common form of poloxalene is Bloat Guard®.
“The preferred delivery would be to have poloxalene commercially mixed into a feed supplement; however, it could be top-dressed onto processed feed in the feed bunk,” Highfill says. “Hand-feeding a supplement may not be possible, so providing poloxalene in a mineral may be the best option.”
If mineral blocks are used, Highfill says producers should encourage daily consumption of the proper poloxalene amount by removing all salt and other mineral sources.
As for the common practice of feeding hay on wheat pasture to combat bloat, Highfill says OSU studies have shown feeding hay really has no significant effect on reducing bloat.
“Some stocker cattle are just much more sensitive to bloat than others,” Highfill says. “If these animals survive the early part of an outbreak, they should be removed from wheat pasture as they will probably be susceptible to bloat the entire grazing period.”