Producers with lush, rapidly growing pastures with high legume contents should be aware of an increased risk of bloat with improved seasonal conditions and a promising outlook throughout southern states.
While there are some products available that may help to treat bloat, the best strategy is prevention. Hence, targeted management will ensure livestock are not affected and producers are still getting returns from their pastures in good seasons.
What is bloat?
Bloat is a condition that can affect both cattle and sheep, but is more severe in cattle, and is caused by an inability to eructate (“burp”) a build-up of gas in the rumen, which can either be free or frothy, causing pressure on the diaphragm, disrupting breathing.
Bloat can cause severe discomfort in livestock and, in advanced cases, death.
What causes bloat?
The most common form is frothy bloat and occurs when a stable foam is created by the ingestion of legume pastures such as lucerne, medics, clover and lush grasses, which trap natural gases that cannot be belched up.
There are some distinctive clinical signs of bloat in animals grazing high-risk pastures, including:
- distension in the left upper flank
- cattle not grazing and reluctant to move
- cattle appear distressed as the condition is painful and they may be agitated and vocalise or rub their sides against objects such as tree stumps
- strain when urinating or defecating
- sudden death.
If cattle are in distress, this must be remedied, and veterinary advice should be obtained. While signs of bloat are usually obvious, other causes of death from similar clinical signs, such as nitrate poisoning and clostridial diseases, can occur. If producers are unsure, a veterinary examination can help determine the condition.
Producers concerned about the risk of bloat should take an integrated approach to preventing it this season. Management strategies for prevention include:
- Gain professional advice to determine bloat risk of pasture.
- Assess and identify high-risk pastures for bloat, especially lush, growing pastures with a high legume content, such as lucerne and sub-clover.
- Avoid grazing high-risk pastures during their growing stage – mature pastures are lower risk.
- If grazing high-risk pastures, apply mineral oil pasture sprays before grazing and treat trough water with a bloat oil formula.
- Bloat blocks/ licks and anti-foaming supplements may be of benefit.
- Limit grazing time or implement strip-grazing. (Note: animals can be affected by bloat in less than one hour of heavy grazing, so intense monitoring is recommended).
- Ensure livestock have access to roughage such as hay. With higher risk conditions prevalent, do not put hungry animals onto that pasture. Cattle can be filled on roughage before being turned onto pasture to prevent them gorging as heavily.
- With pasture management, aim towards grass-legume mixtures with no more than 40% legumes, and incorporate bloat-resistant legumes, such as Lotus corniculatis, into pasture mixes.
When using products, labels should be read and caution should be taken. Products should be used alongside strong management practices for the prevention of bloat.
The prevention of bloat should be of foremost importance for producers, but in cases where bloat has occurred, there are a number of treatment options, including:
- removing cattle from pastures immediately if signs of bloat occur
- bloat drench may provide relief in cases with early symptoms
- veterinary application of stomach tubes, or trocar-and-cannula into the left paralumbar fossa.
A list of available treatment products and management options are available in NSW DPI’s Bloat in cattle and sheep.
Although bloat is of the greatest risk when pastures are growing and lush, producers should be mindful that issues can persist after the perceived ‘danger period’ has elapsed.
Prolonged wet seasons and green pastures can still create bloat issues, so careful monitoring and management should remain.
Ensure 5-in-1 vaccinations are up-to-date to reduce the chance of other diseases causing similar symptoms to bloat and creating confusion.
Help out with bloat research
Charles Sturt University is conducting research to assess the impact of bloat in Australian beef production systems, and are inviting participation in a survey to share thoughts on bloat. The survey can be accessed at https://www.research.net/r/Bloat_survey, takes approximately 10–15 minutes to complete, and knowledge of bloat is not required
Lucerne management this season: