During the second half of the grazing season, pastures are often lush and high in legume content which, if not managed correctly, can cause bloat in your herd.
High legume content is found in clover-sown fields with a clover content over 40%. High legume content is also often present in multispecies paddocks.
When high legume content is ingested, ruminant animals produce larger volumes of gas, such as CO2 and methane.
This gas is usually either belched up or passed through the gastrointestinal tract.
However, if something prevents gas escaping from the rumen, bloat occurs.
There are two types of bloat: glassy bloat, which is less common; and frothy bloat, which is more familiar to beef farmers.
Glassy bloat occurs when something obstructs the animal from belching, usually an object lodged in their tract.
Frothy bloat occurs when a foam develops on top of the rumen liquid and blocks the release of gas.
Bloat can occur quite rapidly, placing pressure on the lungs and the heart of your animals, and can turn fatal within 15 minutes.
Avoiding bloat
To reduce the risk of the digestive disorder occurring, farmers should use methods such as avoiding letting hungry animals into pastures ad lib, using strip wires when allocating grass, and ensuring fibre is included in the diet.
Farmers grazing clover/multispecies sward paddocks should avoid moving animals straight from a grass-only pasture to a mixture with high clover content.
Farmers should also note cows are at higher risk of bloat when dry matter percentage is low after rain or heavy dew.
It is often seen as common practice on dairy farms to provide bloat oil to to the herd. However, if a beef farmer feels their herd is at risk they should be supplying bloat oil through water troughs also.
It is advisable to feed silage or concentrates as a buffer when animals are grazing paddocks with high legume content to improve fibre in the diet.
Identify high risk paddocks and monitor your cattle when grazing these, regularly checking the herd within first three hours of grazing.
Symptoms and treatment
An animal with bloat is typically recognised by having a swollen left abomasum, and the animal displays sign of pain and discomfort, and is bellowing.
Sometimes death can be the first symptom a farmer sees. However, it is crucial to check the rest of the herd for for the disorder if this happens as there could be more cases.
If an animal is displaying signs of bloat, it must be treated as an emergency.
Walk the cow back to the yard slowly as walking can take the pressure off slightly.
Once in the yard, animals with frothy bloat should be administered an anti-foaming agent via a stomach tube.
In rare cases, a vet may need to insert a trochar and cannula into the side of the rumen to expel reluctant gas.
If there is an outbreak of the disorder, remove all animals from the pasture and put them onto a high-fibre diet, advisably hay or straw.
Do not let cows back into the paddock in which bloat occurred for at least 10 days.
