is an important issue for beef and dairy producers, since
parasites contribute to production loss and reduced
Anthelmintic wormers are an important part of parasite
control, but cattle producers must not repeat the mistakes
of the sheep industry by relying on anthelmintics alone, nor
being too liberal with their use.
To avoid creating a situation where wormers stop working,
beef and dairy producers should familiarise themselves
with the basic principles of anthelmintic resistance, and
understand how to create a sustainable parasite control
plan for their livestock.
Appropriate use of anthelmintics means using them as part
of an integrated parasite control plan, says Ms Timothy.
One that also considers the impact of worm treatments on
the grazing environment, to preserve their e ectiveness for
the long term.
process of avoiding resistance, and it's worth remembering
that cattle are frequently infected by several parasite
species at the same time.
species Cooperia oncophora, Ostertagia ostertagi, and
lungworm Dictyocaulus viviparus.
All of these species can inhibit an animal's growth and
reduce productivity, but co-infection with Cooperia and
Ostertagia can cause a larger reduction in growth rates in
calves than either species does individually. It is therefore
important to address both in control programmes.
It's not possible to tell which species are infecting the
herd without investigation and the use of some diagnostic
tests. The farm's vet or local animal health advisor can help
identify the type of parasites present on farm, and the level
of burden, to create a personalised control plan.
ttle producersntic resistance eractices is essential to ensure
productivity for dairy producers
characteristic, where a genetic `trait' is passed from one
generation to the next via the worm genome.
When worms come into contact with an anthelmintic
treatment, susceptible worms die, while less sensitive
worms and those carrying resistance genes will survive.
Those that survive will reproduce, increasing the
percentage of the population carrying resistant genes, until
a population may be entirely resistant to that anthelmintic.
This process of selecting for anthelmintic-resistance genes
in worms can be sped up by the repeated use of the same
wormer compound, and by treating cattle and immediately
moving them to clean pasture.