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Frothy bloat in cattle

Updated: Aug 31, 2023

Bloat is a relatively common condition in spring, a­ffecting cattle more than any other species.

In the biggest of their stomachs (the rumen) live a lot of microorganisms. When all is well, the microorganisms will thrive and multiply. In return for these favours, the cow will eat a part of them, after they have transformed non digestible cellulose into high-quality food.

A by-product of this process is gas, which under normal circumstances the cow will bulge out approx. twice every five minutes. However, certain conditions can interfere with this, which for the cow can mean serious trouble.

When eating a high fibre diet, cattle produce a massive amount of saliva. Saliva is very important as it facilitates digestion and keeps a constant pH.

During spring we typically grow pasture rich in carbohydrates and protein but lacking good amounts of fibre. After a cold night and heavy dew, the low fibre grass eaten mixed with very little saliva (the cow’s own anti-bloat agent) are ideal conditions to develop what’s known as frothy bloat. When this happens, air bubbles are trapped between layers causing the rumen to swell dramatically and a large bulge in the abdomen will develop rapidly, showing in the left flank. The cow will become restless, stop eating and will try frequently to urinate and defecate.

As the distension becomes worse, the animal shows severe breathing difficulties and may groan and grind her teeth because of pain and discomfort. Cattle can soon die from heart or lung failure due to the pressure of the swollen rumen on these organs.

So what can we do to minimise the risk of developing this life-threatening condition?

  • Avoid gorging of high-risk pastures by hungry cows. This is more likely to happen on fast spring rounds when feed is tight.

  • Ensure the diet contains adequate fibre. Adding hay or silage will provide additional fibre with the added benefit of improving rumen function.

  • Avoid high-risk paddocks as the first feed in the morning. Wait until pasture has dried up before putting cows on (afternoon); alternatively graze high-risk pastures with poorer-quality pastures.

  • Rumen modifiers such as Rumensin bullets are oral products that alter the rumen micro population make-up by increasing the number of efficient energy-producing bacteria and reducing the population of less efficient, more gas-producing bacteria.

  • Bloat detergents – modern bloat detergents (e.g. Bloatenz) act by breaking down the stable foam in the rumen.

If you notice an animal with early signs of bloat, drench them with bloat oil or 100ml of vegetable oil if this is not available. Remove the herd from the o­ffending pasture and feed hay or mature grass/silage. Animals in severe distress will need immediate attention. Speak to your vet now so that you are prepared.

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