Over the previous 6-7 months, we have had lots of parasite factories (lambs and calves) grazing our pastures. These young animals do not yet have an immunity to parasites and provide high levels of contamination onto the pastures.  

Autumn weather also provides an excellent environment for parasite eggs to hatch and for larval development.    

One thing we hear from farmers is that they want to “challenge their replacement stock” so that they develop a good immunity. However, it is very important not to put undue pressure on these stock, as they may become sick or stressed and put so much energy into surviving the challenge that their immunity is not able to develop.   

In most New Zealand farming systems, the key is to keep the parasite intake low enough to allow great health, and strong immunity development. They only need a tiny level of exposure to achieve this.   

Autumn is the perfect time to strategically use a ‘novel’ or ‘knock out’ drench, such as Startect for sheep, or Zolvix Plus for sheep and cattle. It is basically a 'clean-out' drench used to kill any parasites that have survived previous drenches. 

Parasites are particularly cunning. They are in-sync with pasture growth, and it is no coincidence that they are ready to infect at the same time the pasture has regrown and is ready for grazing. Whenever possible, don’t follow lambs with lambs or calves with calves. 

Different parasite species will dominate at different times of the year. Trichostrongylus (Trichs) love a good autumn! Consider doing an autumn drench check, as earlier checks may not have picked up this parasite. We recommend doing a drench check at the start, middle and end of the season.

We’re happy to discuss any of these points with you at any time – please get in touch if you’d like more guidance relating to your farm’s situation.