Department of Agriculture, Western Australia
Preventing bloat in cattle
Farmnote No 83/93
 
By Officers of Agriculture Western Australia 
Bloat most commonly affects cattle grazing lush, clover-dominant pasture. The onset is usually rapid and always unpredictable. The rumen distends when excessive amounts of gas are produced which the animal is unable to expel. In severe cases, the bloated animal can die from heart failure and asphyxiation resulting from internal pressure on the diaphragm and the lungs.
Pastures that have a high protein, and water and starch content, but are low in fibre most often cause the condition. When cattle do not consume enough roughage, the amount of saliva they produce is reduced and the acidity of the rumen increases. Any grass in the pasture can reduce the risk of bloat.
Bloat is most common in young cattle, especially weaners and yearlings. "Gassing up" can affect cows on both sides but they often survive the condition.
Control methods
Several measures can be taken to prevent bloat in cattle, such as planning the movement of stock between paddocks, vaccination and feeding hay. Preparations such as proprietary blocks and bloat oils and capsules are also useful.
Stock management
Bloat occurs most often when cattle with empty stomachs overeat, after being released from cattle yards, or when they are moved onto fresh, legume-dominant pasture in a new paddock. To avoid these dangers:
* feed the cattle hay before releasing them from the yards; 
* move cattle onto new paddocks in the middle of the day, just after their peak morning graze and before their evening graze; and 
* watch the stock closely for signs of "gassing up". Bloat usually affects the left hand side first. Once it affects both sides, the animal's breathing becomes heavy and it can die quickly. 
Vaccinate for pulpy kidney
Vaccinating cattle for pulpy kidney can reduce the incidence of bloat. If bloat could become a problem, vaccinate with a clostridial vaccine that includes pulpy kidney. For cattle that have never been vaccinated, two injections six to eight weeks apart will be needed. If they have been vaccinated previously, they should have a booster.
Feeding hay
Bloat is the result of a roughage deficiency in the diet. Animals will not always eat hay readily in the spring, but it will help if they eat it before grazing clover-dominant pasture. Feed one bale of hay for 20 head with a mixture of bloat oil and water applied.
Proprietary blocks
Proprietary blocks are expensive but they are popular if bloat is only a short term risk. Introduce blocks to the paddock up to three weeks before the main risk period to ensure that most cattle have a regular intake.
Bloat oils (pluronics)
Several bloat oils are marketed, for example, Teric Bloat Liquid(r). Adding pluronics to drinking water is only effective where troughs are the only source of water in the paddock. Start treatment before the main risk period for bloat to allow cattle to adapt to the taste in the water.
Alternatively, a mixture of 136 L of water, 45 to 70 L of molasses and 2.5 to 3 L of bloat oil (pluronic) can be fed through a roller drum. The mixture will last 8 to 10 days for 30 head.
Pluronics may be sprayed on pasture daily to help reduce the incidence of bloat.
Bloat capsules
Rumensin(r) bloat capsules deliver a regulated daily dose of monensin to the animal. The capsules are not 100 per cent effective in preventing bloat but they do significantly reduce the incidence of bloat and deaths from bloat.
The capsules also have a positive effect on feed utilisation and weight gain (cattle can gain more than 8.5 kg in 100 days) which covers the cost of the capsule.
The capsules are administered by mouth into the rumen and are not recommended for cattle weighing less than 200 kg. They are registered for use on beef and dairy cattle.
 
Note: Mention of trade names does not imply endorsement or preference of any company's product by Agriculture Western Australia, and any omission of a trade name is unintentional. Recommendations are current at time of publishing
 


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