Any time cattle are consuming highly digestible feedstuffs and forages the potential for frothy bloat exists. Foamy or frothy bloat reduces performance and can potentially lead to death of cattle. Frothy bloat occurs when the gases normally produced during ruminal fermentation cannot be expelled from the rumen by eruption (belching). At the onset of bloat, cattle may cease eating and the bloat may dissipate. As the severity of bloat increases, the rumen becomes more distended and the level of discomfort increases. If no intervention occurs, death can result from respiratory distress and heart failure.
Frothy bloat on pasture is usually associated with actively growing, highly digestible forages that contain low fiber and relatively high crude protein levels. Among these forages are small grains forages and legumes such as alfalfa and red and white clover. Carbohydrates and soluble proteins from these feeds are rapidly degraded and fermented in the rumen. Small grains bloat is typically a problem in late winter-early spring when the forage is coming out of winter dormancy. Occasionally fall-winter bloat can be a problem.
The occurrence of bloat is affected by a number of factors – soil fertility, climatic conditions, stage of plant development, grazing management and animal disposition – among others. Because of the multiple factors, reducing or preventing bloat may require multiple management approaches and the success, or lack thereof, can vary from year-to-year and operation-to-operation.
Grazing programs should focus on turn-out practices and forage availability. Prior to turning cattle onto pasture ensure that they are full. This will tend to limit immediate grazing activity and forage consumption. During bloat risk periods, providing access to hay or other forages may reduce the occurrence of bloat. Assuming the cattle will consume the hay-forage, consumption of the bloat-provocative forage may be reduced and hence reduce the risk of bloat.
Poloxalene (Bloatguard) is a mild detergent that reduces the foam in the rumen and thereby reducing the incidence of bloat. It is available in different forms – blocks, mineral supplements, liquids, top dresses. To be effective, cattle must consume a sufficient amount of poloxalene daily. Poloxalene in a self-fed form will probably never totally prevent bloat because of the variation in daily consumption by individual animals. Hand-feeding poloxalene in a larger volume of feed will increase the consistency of daily intake.
Surfactants, anti-foaming agents, have been used successfully in some grazing situations. In order for surfactants to be effective, like poloxalene, they must be consumed on a daily basis. Water treatments are effective as long as the treated water is the only source of water and the surfactant concentrations are maintained.
Ionophore feed additives may also aid in bloat prevention by reducing microbial gas production in the rumen. Ionophores can be delivered in blocks, mineral supplements, pelleted supplements and mixed feeds. An additional benefit of ionophores is that they will improve daily weight gain. As with poloxalene, these feed additives will not totally eliminate the occurrence of bloat.
Salt consumption may also reduce the incidence of bloat. A survey of Oklahoma producers indicated that bloat incidence was lower when salt was available. Data has also shown that cattle grazing wheat and consuming a complete mineral balanced for wheat pasture, which contains salt, gain more rapidly than cattle consuming salt alone and inclusion of Rumensin further improved gains. So offering a mineral supplement provides a means of delivering salt as well as an ionophore, both of which may help reduce bloat prevalence, as well as improve performance.
Some cattle are predisposed to bloat. This may reflect physiological differences, differences in ruminal microbial populations, differences in forage selection and forage intake, or other factors. If animals are chronic bloaters the best approach is to remove them from the group.
Several factors, acting in combination or individually, can lead to a bloat problem. No one single management practice will be effective all of the time. The only 100 percent effective means of stopping bloat is to remove the cattle from a bloat provocative pasture. Knowledge of when bloat occurs and why it occurs can help in developing and implementing a management plan to reduce occurrence.