19 August 1997

Displaced abomasums turn spotlight on diets

AN INCREASE in left displaced abomasums seen by dairy vets may indicate that high yielding cows need extra care with feeding and hygiene at calving.

Independent vet consultant Tony Andrews reports that cases of left displaced abomasums are up 50% on last year.

The disorder is unusual in cows yielding under 6000 litres and appears most common in cows that reach peak milk production quickly, he says.

Although the diseases direct cause is not fully understood, poor gut fill is thought to allow the abomasum to slip underneath the rumen.

Gloucester-based vet Chris Watson has also seen an increase in cases of displaced abomasums this summer compared with previous years. Cows suffering milk fever or that are dirty after calving, with whites, seem at highest risk, he says.

The cows ration could be a direct cause, or indirectly involved – increasing risks of milk fever and difficult calvings. He advises paying extra attention to dry cow and post-calving rations.

"Dry cow rations should fill the rumen, and must be regulated carefully so that calcium is restricted, and magnesium levels are kept up."

Ensure this diet is high in fibre, preferably feeding silage to acidify the rumen and also help to reduce milk fever. Then introduce the milking ration slowly after calving, ensuring maize-based rations are high enough in fibre to give rumen fill, he says.

Hampshire-based vet Jonathan Harwood, who has also seen more displaced abomasums this summer, adds that three-quarters of those cases occurred in cows with post-calving womb infections.

Many of these infections can be prevented by avoiding over-fat cows at calving, choosing sires for easy calving, and ensuring good hygiene at calving. "Wash hands and arms with soapy water before interfering with cows at calving," he says. &#42

Dairy diets need watching warn vets who report a 50% increase in displaced abomasums this year.