Spring is the New Year for worms.  As the weather warms and spring rain continues, parasites at the larvae stage that have been slumbering in your pasture come to life and resume their life cycle. They multiply furiously through spring and summer. If not managed successfully, they can reach very high, potentially fatal numbers for your livestock later in the autumn.

Management Plans

The challenge is to minimise the impact that worms have on production, while preserving the effectiveness of available drenches.  Basing worm management on a rigid drench-only programmes is not the most effective, cost-effective or sustainable way to manage parasites.  Worm management plans also need to include:

  • a way of monitoring the effectiveness of the drench (such as Faecal Egg Counting, and weighing)
  • choice of an effective product
  • timing of drenching
  • what mobs or individuals within mobs are drenched or not, and
  • route of administration

Grazing options (eg: minimising pasture contamination) should be considered as these are very important components of parasite control.


Ostertagia can be a problem for cattle in the spring, with most yearling cattle being challenged.  Faecal egg counts may not be a reliable indicator, so a routine drench of all yearlings is a reasonable tactic. Most two year old cattle should be immune to worms, but target under-performing, lighter animals who may be susceptible.

Travelling stock should be quarantine drenched with a triple-active drench. Do this either on their return from grazing, or on their arrival at their new grazing property.   This should be followed by holding in a quarantine area for 24 hours, and subsequent grazing on pasture that is not necessarily “clean”.

In preparation for weaning calves and lambs, decide what drench to use and where to graze them after weaning, based on previous experience and monitor with regular weighing and faecal egg counting.

Deer & Parasites

Recommendations for drenching deer have been reconsidered and revised in recent years. Unfortunately after two decades of using a single active pour-on that is no longer effective, with an average efficacy of only 55% – or put another way roughly only 1 in every 2 worms are still susceptible! The newly recommended protocol is a cocktail of treatments including an injectable and a concoction of oral drenches which are “off-label” but effective.

Goats & Parasites

Drench protocols for goats have also been thoroughly revised by the “Wormwise” team.  A new booklet has been produced and is available on the Beef + Lamb website.  It is a very detailed review of parasites, drenches and drench resistance in goats and a “must-have” for any goat owner.

If you would like more information please give our vets a call and come in and see us and we’ll talk you through it.

Phil Rennie BVSc