Frothy bloat in cattle

Written by Bas van Luijk, Veterinarian at East Coast Farm Vets

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Bloat is a common condition in cattle, particularly during spring when pastures are lush. It predominantly affects cattle due to the unique structure of their stomach, specifically the rumen, which is home to a thriving population of microorganisms.

When all is well, the microorganisms will thrive and multiply breaking down fibrous material, converting it into digestible nutrients for the cow, with gas as a by-product. Typically, cows release this gas by belching approximately twice every five minutes. However, certain conditions can disrupt this process, leading to potentially serious consequences.

Cattle on a high-fiber diet produce large amounts of saliva, which aids digestion and helps maintain a stable rumen pH. During spring, pastures are often rich in carbohydrates and protein but low in fiber. After a cold night and heavy dew, the low fibre grass eaten mixed with very little saliva (the cow’s own anti-bloat agent) can set the stage for developing 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.

A cow with frothy bloat will stop eating, become restless, and will try frequently to urinate or defecate.

As the distension becomes worse, the animal will show severe breathing difficulties and may groan and grind her teeth because of pain and discomfort. Without timely intervention, the pressure from the bloated rumen can lead to heart or lung failure, resulting in death.

So what can we do to minimise the risk of developing frothy bloat?

• Control grazing on high-risk pastures.  Hungry cows are more likely to gorge themselves on high-risk spring pastures, especially during quick rotation when feed is limited.

• Ensure adequate fiber intake. Supplementing the diet with hay or silage provides additional fiber, which not only reduces bloat risk but also enhances 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.

• Use rumen modifiers. Products like Rumensin capsules help alter the rumen’s microbial balance, promoting efficient energy-producing bacteria while reducing gas-producing types.

• Administer bloat detergents. Modern products such as Bloatenz help break down the foam that traps gas in the rumen.

If you notice a cow showing early signs of bloat, drench it with bloat oil or, if unavailable, 250-500ml of vegetable oil (depending on the size of the cow). Quickly remove the herd from the problematic pasture and offer hay or mature grass/silage. Severely affected animals require urgent veterinary attention.

Discuss bloat management with your vet in advance to ensure you’re familiar with the signs and well-prepared.