Bloat in cattle

We have seen an early onset of bloat in cattle this year. After the mild winter, pasture has an abundance of legumes (clover) at the moment and once the rain stops and sun comes out, the clover is going to grow at even faster rates.

Bloat is the over-distention of the rumen caused by the formation of a stable foam. Once a foam has formed, gas produced in the normal fermentation process is unable to be “burped” out. The foam is caused by a foaming agent on the leaves of the legumes such as clover and lucerne.

Usually the first sign of bloat is swelling in the left sided paunch of the cattle beast. The animal becomes uncomfortable very quickly. Signs of this include getting up and down frequently, restless, vocalisation looking at flank and kicking at their belly. Death can occur within 15-20 minutes due to suffocation and lack of oxygen to lungs owed to pressure of the rumen pushing on the lungs and heart.

Treatment is urgent. Drench affected animals with 200ml of vegetable or mineral oil. If the animal cannot swallow, a large bore needle will need to be injected on the left paunch to allow the pressure to escape. The oil can then be injected into the rumen via the needle. Remove all animals off the pasture.
There are various ways to control bloat. Beef farmers require less intensive methods than dairy farmers and as such there are only two or three options. Removing animals from bloat-inducing pastures or treating animals with an anti-bloat capsule. For some farmers, spraying pasture with oil may be an option as well.

Anti-bloat capsules contain monensin, which is a rumen modifier. It changes the rumen population of bacteria resulting in less gas being produced. These capsules last for 100 days. As with sheep capsules, they can be regurgitated and at $20 odd dollars a pop, it is a good idea to write the tag number on the capsule so you know which animal has regurgitated their capsule. As with all bloat control methods, anti-bloat capsules do not provide 100% protection. A nice side effect of the capsules is a slight increase in animal production.

Some farmers believe just giving hay is an effective method of control. It is true that hay will decrease appetite for bloat-prone pastures but there will be animals that won’t eat hay because they have a preference for legumes. In most situations, hay feeding will be inadequate if the bloat problem is severe.