Worm egg counts for cattle for effective worming strategies

Cattle

Protect your cattle

All cattle with access to grassland are prone to parasitism. Once on the pasture, infective larvae can survive for over a year. Although the numbers of larvae on ungrazed pastures are likely to decline over the winter, they will not be eliminated. Therefore, a single treatment of an infected animal will not prevent reinfection.

In young calves, parasitism can reduce growth rates by ~30%. In adult cows infections can cause a ~1kg per day drop in dairy milk yield (www.cattleparasites.org.uk).

It is also possible for cattle to be infected by different worms at the same time. A common disease resulting from mixed infections is parasitic gastroenteritis. Severe infections in calves can lead to diarrhoea and significant loss of condition.

Effective worm control

Therefore, WECs should be an essential part of your herd management. They will help you:

  • Only treat your cattle when necessary
  • Use a targeted treatment
  • Predict future heavy worm burdens
  • Monitor the effectiveness of your worm control programme
  • Slow the rate of anthelmintic resistance (AR)

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The aim of effective worm control is to stop worms completing their lifecycle and prevent future contamination.

A WEC tells you about your animal’s parasite burden at a single point in time. However, the lifecycle of a worm includes several larval stages that do not show in WECs. So even if the test results show no evidence of active adult worms, cattle may still carry a worm burden.

Therefore, to build an accurate picture of your animal’s internal health, you should repeat the test regularly.

Worms commonly found in cattle

Osteragia ostertagi (Brown stomach worm)

Notes Infection results in a diseased abomasum leading to Ostertagiosis Type I. Ostertagiosis Type II is a less common but more severe disease seen towards the end of the housing period.
Most commonly affect Young grazing animals.
Signs and symptoms Diarrhoea; weight loss; loss of appetite; failure to thrive.
Can lead to Parasitic gastritis. Ostertagiosis Type II can be fatal.
Control Alternate grazing with sheep. Early season treatment to prevent buildup of larvae on pasture.

Cooperia oncophora

Notes Symptoms associated with Cooperia oncophora are often less obvious than with Ostertagia infections.
Most commonly affect Young grazing calves.
Signs and symptoms Weight loss; failure to thrive.
Can lead to PGE.
Control Alternate grazing with sheep. Early season treatment to prevent buildup of larvae on pasture.

Haemonchus contortus / placei (Barber’s pole worm)

Notes Barber’s pole worm feeds on blood from the host in the abomasum.
Most commonly affect Calves.
Signs and symptoms Anaemia; lethargy; weight loss; oedema.
Can lead to May be fatal
Control Alternate grazing with sheep. Early season treatment to prevent buildup of larvae on pasture.

Trichostrongylus spp.

Notes The parasite feeds on blood from the gastrointestinal tract.
Most commonly affect Young grazing cattle.
Signs and symptoms Persistent watery diarrhoea; weight loss; failure to thrive.
Can lead to May be fatal.
Prevention Alternate grazing with sheep. Early season treatment to prevent buildup of larvae on pasture.

Oesophagostomum radiatum

Notes Adult worms are found in the large intestine.
Most commonly affect Young grazing cattle.
Signs and symptoms Fetid diarrhoea; anaemia; oedema.
Can lead to May be fatal.
Prevention Alternate grazing with sheep. Early season treatment to prevent buildup of larvae on pasture.

Dictyocaulus viviparus (Lungworm)

Notes Lungworm infects the lower respiratory tract.
Most commonly affect Grazing calves.
Signs and symptoms Characteristic coughing.
Can lead to Interstitial emphysema; pulmonary oedema; bronchitis; chronic, non-suppuratic, eosinophilic, granulomas pneumonia; secondary bacterial infection. May be fatal.
Control Appropriate anthelmintic treatment.

Fasciola hepatica (Liver fluke)

Notes Liver fluke cause considerable economic loss to farmers in the UK and worldwide. They are trematode parasites responsible for the disease fasciolosis. Liver fluke use snails as an intermediate host, so are usually more prevalent on land that doesn’t drain well and during wet summers. Infective larvae can survive on pasture for several months.

However, prevalence of the disease is increasing, possibly due to changes in climate and farming practises; an increase in animal movement around the UK; and the increase of AR in fluke.

Most commonly affect Cattle are not as susceptible to liver fluke as sheep, but infection can still be severe.
Signs and symptoms Weight loss; anaemia; drop in milk production.
Can lead to Calcification of bile ducts in chronic infection.
Control Prevent access to snail habitats.