You may not have heard of it but this bacteria is the most commonly diagnosed cause of abortion in Scottish cattle. SRUC Veterinary Services data shows that over a 10 year period it accounted for one third of all infectious abortion diagnoses. Bacillus licheniformis abortions are most common in housed, pit silage fed, spring calving beef cows in the last 2 months of pregnancy. It can also have a role in still births.
Bacillus licheniformis is present on all farms – in the environment, slurry, silage and water troughs. Taking the following steps can help to reduce cow exposure to it:
- Feed the best available silage to late pregnant cows.
- Feed out the silage face in as short a time as possible. Don’t work left to right then right to left.
- Use a shear grab.
- Never feed silage that is obviously mouldy/slimy in appearance.
- Beware of silage from the top and sides of the pit – consider feeding it to youngstock.
- Clean away any uneaten silage before adding more.
- Clean out water troughs frequently – stir up the water and see how much debris is present on the bottom.
Testing has shown that:
- Big bales often contain lower numbers of Bacillus licheniformis bacteria than pit silage.
- A sample of slimy silage contained 36 million Bacillus licheniformis bacteria per gram.
- A sample of debris from the bottom of a water trough contained 5 million Bacillus licheniformis bacteria per gram.
Bacillus licheniformis abortions are much less of a problem in dairy herds. There may be a role for silage additives in reducing the risk, but more research is needed to confirm this.
Heather Stevenson, email@example.com
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