The following are the results from a farm which buys in large numbers of store lambs, from a number of different sources. This case study follows one batch of lambs bought in April. They had been drenched with Switch prior to leaving the farm of origin. Due to concerns about Barber’s pole and a previous concern about the efficacy of Exodus, they were given Genesis Ultra on arrival.
What we can see from these results:
1. High worm burdens were causing acute deaths in lambs recently drenched.
2. Switch was not effective in controlling the worm infection and double drench resistance is present.
3. Startect did effectively kill all the worms in the infected lambs.
4. Trichostrongylus can be an extremely pathogenic worm and difficult to control as some species infect both cattle and sheep.
5. Working out what was affecting these lambs required considerable investigation and lab work.
Where to go from here?
1. A full FECRT needs to be performed next year to see the full extent of resistance.
2. Double drench resistance to Abamectin and Levamisole is present on this farm and there is a good chance that this may be a triple resistance situation. So Matrix cannot be relied upon as a quarantine or knockout drench and its use needs to be ended.
3. Alternative measures to control and manipulate the worm population on this farm need to be used as much as possible to prevent the reliance on Startect. This is especially important as the future access to this product may be limited.
4. During Barber’s Pole season a combination of products e.g. Exodus and Startect may have to be used and close attention to FEC is important to avoid unnecessary drenching.
5. The use of REFUGIA is vital on this farm. Measures that can be used are:
– Use of adult cows over the winter to ‘clean pastures’.
– Leaving a small portion of each lamb mob undrenched at each drenching.
– Buying in of un-drenched lambs to repopulate the farm with ‘killable’ worms.
6. Close, continued monitoring of worm levels in lambs before and after drenching is key and continue with larval cultures to ensure a more diverse worm population has built up.
If you would like to know more about our FEC Monitoring service, please talk to your lead Anexa vet – we’re here to help.
