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Beware of bloat

South East Local Land Services is advising Braidwood district land managers to be aware that stock are entering a high-risk period for bloat, with the arrival of spring and the recent high levels of rainfall.

District Veterinarian, Kate Sawford explains ruminants produce large volumes of gas during digestion, which is either belched up or passes through the digestive system.

“If something interferes with the escape of gas from the rumen bloat will occur,” Ms Sawford said.

“Grazing of immature, rapidly growing clover or lucerne in early maturity (i.e. pre-bloom) is the biggest single risk factor for bloat in cattle.  The reason is that foaming agents in rapidly growing legumes, as well as some grasses, cause a stable foam to form in the rumen.  Gas gets trapped in the small bubbles in this foam and the animal cannot then belch up the gas.  Pressure will build up and cause the rumen to swell.”

Bloat does occur in sheep but is generally less severe compared to the disease in cattle.

“Cattle and sheep with bloat may be distended on the left side of the body, reluctant to move, or in distress,” Ms Sawford said.

“They may also cease to graze.  They may strain to urinate and defecate, breathe rapidly, or stagger. In severe cases they may go down or be found dead. Sometimes finding dead stock is the first sign of the bloat.

“High-risk conditions for bloat are the same as those for outbreaks of enterotoxaemia, or pulpy kidney, so make sure cattle and sheep have been vaccinated against clostridial diseases (i.e. with 5-in-1, 6-in-1, 7-in-1 or 8-in-1) according to the manufacturer’s directions prior to putting them out onto lush pasture this spring.

“Stock that are mildly affected can be treated orally with an anti-bloat preparation such as vegetable or mineral oil, or a commercially available product.  Animals need to be kept moving after treatment to ensure the preparation mixes with the rumen contents.

“Bloated animals showing signs of distress need immediate veterinary attention so a stomach tube can be passed to remove the excess gas and enable delivery of anti-bloat preparations.  In severe cases a trochar and cannula will need to be inserted immediately into the rumen high on the left flank

“If a trochar and cannula are not adequate to relieve the pressure, a pointed broad-blade knife can be used to make a stab incision that is then enlarged by turning the knife 90 degrees.  After the gas and froth has been removed, an anti-bloat preparation is poured into the rumen to help break down the remaining froth/foam.  In such cases there usually isn’t enough time to wait for the vet to administer treatment, but one will be required to clear out the abdominal cavity, clean and stitch the wound, and give antibiotics to prevent infection.

“When pasture is considered risky, there are a number of options for bloat prevention that can be used individually or in combination:

  • restrict pasture intake by limiting grazing time or utilizing strip grazing
  • feed up animals with hay before turning onto pasture
  • use a mixture of alcohol ethoxylate and molasses in a licker drum or put out anti-bloat blocks or dry loose licks near stock camps and watering holes.

“Slow-release rumen bloat capsules are once again unavailable this year.

“As the past winter has been particularly difficult in the Braidwood district, remember not to allow hungry cattle access to legume-rich pasture without first thinking about bloat – feed out hay first and then observe cattle on pasture closely for any signs of bloat.”


Media contact: Kate Sawford, 0427 422 530