worm testing lab Asutralia

The cost of worms

The estimated losses due to internal parasites in Australian sheep and cattle alone is $A1 billion and worldwide it's tens of billions (Roeber et al., 2013). A study published by Meat and Livestock Australia Limited (Lane et al., 2015) estimates the total losses per annum due to internal parasites to be as follows:

  • Cattle $A93.6 million with production losses ranging from $0.44 - $3.59 per animal
  • Sheep $A436 million with production losses ranging from $1.29 - $28.29 per animal
  • Goats $A2.54 million with production losses ranging from $0 - $5.34 per animal

Note: There is no production loss data for horses but the estimated annual costs of worming ranges from $A15.00 - $120.00 per animal. 

Signs of worm infection can often go unnoticed until the problem becomes severe. As you can see below, by the time the signs of worms (clinical effects) are noticed in the herd/mob, the producer has already experienced significant losses in productivity.

 worm egg count Queensland

Zoitis. 2019. Monitoring for Worms. [ONLINE] Available at: https://www.zoetis.com.au/livestock-solutions/sheep/effective-parasite-management/monitoring-for-worms.aspx. [Accessed 27 October 2019].

Some animals naturally carry a large burden of these worms without showing any symptoms of infestation at all. These ‘subclinical effects’ may not be noticeable and may include any of the following:

  • Lower feed conversion rates
  • Lower growth rates
  • Reduced production and quality of wool
  • Reduced lambing percentages
  • Poor growth rate of lambs
  • Increased costs for replacement stock
  • Reduced production and quality of milk in dairy cattle

Just one adult female roundworm can shed up to 5,000 - 10,000 eggs per day! (eg. Barbers Pole worm). Other animals are known as ‘high shedders’ and they may well be infecting the pasture and other individuals in the mob/herd that may not have the same natural immunity further contributing to these production losses.

It is an economic advantage to monitor your animals to identify when the opportune time to drench is (without ‘over-drenching’ and contributing to the risk of developing ‘worm-resistance’ on your property). It is also economically viable to perform a ‘Drench Resistance Test’ every 1-2 years to identify the most appropriate drench actives to be used on your property.


Lane J. et al. 2015. Priority list of endemic diseases for the red meat industries. Project Report. Meat & Livestock Australia Limited, [Online]. Available at: http://era.daf.qld.gov.au/id/eprint/5030/ [Accessed 1 October 2019].

Roeber F. et al. 2013. Impact of gastrointestinal parasitic nematodes of sheep, and the role of advanced molecular tools for exploring epidemiology and drug resistance – an Australian perspective.. Parasite Vectors, [Online]. 6, 153. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3679956/ [Accessed 1 October 2019].