What causes bloat and how can it be avoided?

With the grazing season in full swing in all parts of the country, cattle can be dotted across the countryside grazing fresh pastures.

While cattle are far healthier and happier outdoors, farmers must remain vigilant and keep a watchful eye for any problems. Earlier this month, we looked at grass tetany – what causes it and how farmers can prevent it.

In the following article, AgriLand caught up with Ronan Gorry, Ireland manager at Terra Nutritech, to – firstly – discuss why bloat becomes an issue and, secondly, what farmers can do to prevent issues arising as a result of bloat.

What is bloat?

Bloat is where the excess gas (methane and CO2) produced can affect normal rumen function. When rumen function becomes unbalanced due to high protein / low fiber intake it can result in a build-up of foam in the rumen.

Bloat causes huge pressure in the chest of ruminants and often leads to cardiogenic shock. It can occur quite rapidly and in severe cases results in death. Remember, one case may be the tip of the iceberg – always be vigilant when there are suspected cases on a farm.

Why does it occur in spring?

Lush pastures, being low in fibre and high in soluble protein, cause a real risk of bloat. Clovers are a significant risk factor and the addition of spring grass which can be high in sugars and water content results in stress on rumen microflora.

The result is the bugs in the rumen are working harder and producing a lot of gas. There may also be less saliva production which can normally act as a buffer in the rumen.

In these conditions, soluble proteins can rise to the top of the rumen becoming insoluble and cause a froth/foam to develop.

How will I know an animal is suffering from bloat?

There are many signs which indicate bloat. Firstly, animals will have a distended left abdomen and cease grazing. They may also be breathing rapidly and have a reluctance to move. 

In addition, animals can appear distressed and have bulging eyes; staggering may also be evident. 

How can farmers prevent or treat bloat?

Spring and early summer are a time to be vigilant and great care should be taken when putting stock into new lush pastures with clover.

The use of strip wires to slowly introduce cattle to clover-rich swards is one option during the risk period and it can be reduced and prevented by good grassland management.

Where possible, avoid letting hungry cows out to lush perennial ryegrass / clover-mixed paddocks. Where grazing lush mixed swards allow cows onto a small section of the field for a few hours to allow their rumen to adapt slowly.

There are very few treatments for bloat, but an increasing number of farmers are feeding bloat oil through drinking water during risk periods – particularly with at-risk swards containing high levels of clover.

The addition of bloat oil into the water is an effective and easy way to prevent bloat in the herd as it acts as an anti-bloating agent.

If you get a suspect case, recheck grazing strategies and reduce the risks. Walking may take the pressure off for a short period until treatment is administered. Animals which are down may need emergency intervention rapidly to relieve the gas.

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