Preventing pasture bloat this spring

As spring arrives so does the increase of lush green pastures. Unfortunately, without correct management, this sudden change in pasture composition can cause problems for ruminant species, particularly cattle. Pasture bloat often occurs when cattle graze pastures high in clover, lucerne or other legumes that are rapidly growing early in the season. They are particularly susceptible when they are not used to these plants in their diet or have reduced roughage intake (such as hay).

The digestion of this young legume growth results in excessive gas production in the rumen that cannot be eructated (burped) out fast enough. This forms a foam within the rumen above the sold or fibrous and liquid layers. The result of this is significant distention of the rumen also known as bloat.

Bloat is a serious condition that can cause severe illness within an hour of exposure to high risk pastures and often results in sudden death if not identified and treated. Initial presentation may include some distention or swelling (particularly on the left side of the abdomen) and signs of discomfort such as getting up and down, kicking at flanks or looking at abdomen. More severe signs include obvious distention, respiratory difficulty, drooling and potentially recumbency and death. Treatment often requires surgical removal of gas and foam via incision into the rumen through the left flank. This is an emergency procedure in many cases and may involve leaving an open incision or a trochar in place. Bloat oil may be used to reduce further foam formation.

In some instances, low grade chronic bloat is seen, often in younger animals that gorge on rich lush pasture and avoid roughage. Younger animals are often higher risk due to gorging; older animals will generally adjust their eating habits once accustomed to new pasture. Prevention of bloat is best practice.

Gradual introduction to rapidly growing pastures with high legume percentages is vital. Also only allowing short grazing periods (eg strip grazing) and ensuring plenty of roughage (eg pasture hay) has been supplied prior is helpful. Monitoring animals closely is also helpful. Anti-bloat treatments can be helpful, such as bloat oils in water or bloat lick blocks can be used, however it is very difficult to ensure therapeutic doses are consumed.