Worm infestations: Don’t guess

Maxine Lyndal-Murphy
Formerly Queensland Government

Many producers believe they can pick when their cattle are affected by worms. This may be so, but there are many other circumstances that cause animals to look ‘wormy’. Poor nutrition is the most common mis-diagnosis of animals being ‘wormy’. Remember, animals do not have to be showing outward signs of a worm infestation before production losses occur.

The most effective and practical method of determining worm burdens is to measure the worm egg level in the dung. Results are expressed as eggs per gram of dung (epg). If egg counts are below 200epg it is unlikely that worms are causing a problem. If egg counts are >200epg it is important to determine what species of worms are present. Different worms cause problems at different infestation levels.

It is recommended that calves be checked at or within a month of weaning and again about a month after the season breaks. The follow-up test is important to ensure worm burdens remain under control.

Worms are generally not considered to be a great problem in cattle over 20 months of age on extensively grazed beef properties. However on some properties in wet years where permanent pastures are continually grazed, stock under 20 months of age may be at risk.

Do you need to drench your cattle?

The decision to drench should be based on a worm egg count. Results from testing over the last 10 years show that 70% of submissions carry very low worm egg counts and require no treatment.

If you do drench, a worm test taken seven days later should have a zero worm egg count if the drench as been effective.

Read more at Know your worms.