Bloat is a form of indigestion marked by excessive accumulation of gas in the rumen of cattle. The build-up of gas in the rumen can be caused by several factors, including:

• Free-gas bloat: This occurs when the esophagus becomes obstructed by incompletely processed or chewed feeds (e.g., potatoes, beets, apples, turnips) and even hay twine. Free-gas bloat can also be caused by a lack of rumen motility, which can be caused by damage to the vagus nerve by pneumonia, hardware disease, or thoracic abscesses.

• Frothy bloat: This happens as the result of a stable foam developing on top of the rumen liquid, which blocks the release of the gas. This is by far the most common form of bloat, and unlike gassy bloat, it is highly seasonal with peaks in the spring and autumn. This is because the foam is formed by breakdown products from rapidly growing forages (particularly legumes such as clover and alfalfa). These increase the viscosity (stickiness) of the rumen fluid and prevent the small bubbles of gas formed by rumen fermentation from coming together to form free gas that can be belched off.

• Acidosis: Acidosis and bloat can be interrelated, with acidosis predisposing animals to bloat. Using management practices that consider the proper amount of grain and roughage in the diet, proper grain selection and processing, use of proper bunk management, use of feed additives, and allowing adequate time between diet transitions can help to limit the occurrence of acidotic bouts in feedlot cattle.

• Grain portion being ground too finely: Cattle consuming feedlot diets may have bloat caused by the grain portion being ground too finely. Fine-ground grains are digested rapidly, causing rapid fermentation and gas production.

Visual signs of bloat in cattle include distension of the left side of the animal as the primary sign, discomfort as indicated by stomping of feet or kicking at the belly, labored breathing, and eventually collapse and death by asphyxiation. Preventing bloat is desirable not only to reduce deaths but also to reduce the negative effect of bloat on cattle performance. Management practices to reduce the incidence or severity of bloat include:

• Preventing pasture bloat: This can be done by managing feed intake, using management practices that consider the proper amount of grain and roughage in the diet, proper grain selection and processing, use of proper bunk management, use of feed additives, and allowing adequate time between diet transiti...