Bloat in cattle develops from gas buildup in the first part of the stomach -- the rumen. Usually, cattle rid themselves of excess gas via belching. Bloat is an emergency -- cattle can die within an hour, so prompt attention is potentially lifesaving. Cows experiencing bloat of either type are in obvious pain and discomfort. Other symptoms include constant bellowing and abdominal distention on the left side.
The most common type of bovine bloat, frothy bloat generally occurs in cattle on pasture. For that reason, cattle are more vulnerable in the spring and fall, when grass is especially lush. Frothy bloat develops when a foam, or froth, forms atop liquids in the rumen and traps gasses.
Certain pasture plants are more likely to cause bloat. These include:
- Winter wheat
- Clover -- including sweet, white, red and alsike varieties.
Gassy bloat more often occurs in feedlot cattle, but it can happen in any bovine, especially calves. If the animal consumes a foreign object that obstructs the esophagus, or gullet, the obstruction renders the cow unable to belch and rid herself of gas. It also can result from certain diseases, such as tetanus, which causes muscles to stiffen. Large amounts of grain and irregular feeding may contribute to this type of bloat. Gassy bloat may occur quite suddenly, and the cow might die before treatment can commence.
Frothy bloat often affects quite a few animals in the herd, since they are all consuming the same forage. Gassy bloat usually affects just one or two bovines.
Bloat Diagnosis and Treatment
Your vet will pass a stomach tube into the animal to determine whether the bloat is frothy or gassy. If it's the latter, the stomach tube generally enables gas to escape. That's not the case with frothy bloat. Additional gassy bloat treatment includes giving the animal probiotics to re-establish gut flora. For frothy bloat, your vet may pass medications that reduce foam through the stomach tube. The animals must be removed from the pasture and given timothy or grass hay.
If a cow chronically bloats, a vet may perform a rumen fistula. This operation consists of opening a hole in the rumen wall to the outside, which allows the gas to escape, relieving pressure in the cow. The hole may be temporary and eventually close over, or kept open permanently.
Preventing bloat consists primarily of pasture management. When creating new pastures, seed them with low-risk forage plants, such as:
- Birdsfoot trefoil
- Perennial ryegrass
- Spring wheat.
Avoid planting or using a pasture consisting of more than 50 percent legumes. Feed your cattle grass hay before letting them into a pasture with legumes -- hungry animals are more likely to gorge.
Use a salt block containing poloxalene to reduce the odds of bloat. For best results, place blocks throughout the pasture, with one for every 10 animals.
Jane Meggitt has been a writer for more than 20 years. In addition to reporting for a major newspaper chain, she has been published in "Horse News," "Suburban Classic," "Hoof Beats," "Equine Journal" and other publications. She has a Bachelor of Arts in English from New York University and an Associate of Arts from the American Academy of Dramatics Arts, New York City.