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Why prepare low worm-risk paddocks?

By Deb Maxwell, Operations Manager, ParaBoss

While many producers across Australia are coming up to lambing or weaning, when low worm-risk paddocks are valuable, other producers are in a position now to think about preparing these paddocks.

On a personal note, I have a sheep property near Guyra, northern NSW, where barber’s pole worm reigns supreme. I have found that low worm-risk paddocks have had a major positive impact on my worm control. Not only have I been able to drop 3 or 4 drenches a year—yes, that big an impact—the preparation has been very easy to do.

The strategies and practices for worm control vary according to your region, but still use common principles across districts. This article considers the benefits of and ways to prepare low worm-risk paddocks for the most susceptible sheep on the property: mainly weaners and lambing ewes.

Classes of sheep that benefit most from low worm-risk paddocks

Weaners, at and in the weeks after weaning, are susceptible because they have an immature immune response to worms, suffer the stress of separation from their mother, and generally face either high summer worm burdens in the north or hot, dry summers with lower nutrition in the south. In southern Australia, winter weaners are very susceptible after the break of the season, when they may be in light condition and are normally faced with a large winter worm challenge.

Lambing ewes are highly susceptible to worms as their natural immunity drops considerably around lambing time and into lactation. This is typically worse for maiden ewes and ewes rearing multiple lambs.

Preparing low worm-risk paddocks for use by these classes when they are most susceptible provides two major benefits. Firstly, the sheep themselves will face a lower worm challenge, allowing for higher production (milk and lamb growth) and it provides the flexibility to use short-acting, rather than an annual reliance on long-acting, drenches as a pre-lambing treatment (where this is given). The benefits of this are also felt as better management to slow drench resistance.

Secondly, with a lower worm burden than if they were on unprepared pastures, these more susceptible animals won’t be adding the large level of worm contamination to the paddock that they otherwise would have. This greatly reduces the build up of worms over the season that contributes to later problems (and the need for more drenching).

Preparing low worm-risk paddocks

Preparation involves identifying the weaning or lambing paddocks in advance, then using them in a way that prevents further contamination with worm eggs for 3 to 6 months before weaning/lambing/for winter weaners. During this time, you are aiming to have over 90% of the eggs and larvae already on the pasture die, and with no further contamination, a low worm-risk paddock is produced.

Paddocks don’t have to stay empty! Cattle, or even sheep (for a period of time after an effective short-acting treatment or a longer period after an effective long-acting treatment) can graze them, and in some locations/times (very hot and dry or very cold), even wormy sheep can be grazed there. They can be used for crops or hay or spelled for a few weeks to allow new growth.

If you have multiple lambing and weaning paddocks, don’t be overwhelmed—just try one paddock for one group next year and see how it compares.

The time of year, duration of preparation and sheep destined to use these paddocks varies according to region. Your Program in WormBoss describes quite simply what to do to prepare low worm-risk paddocks.

The WormBoss Management Tools section also has a more detailed article on using grazing management to prepare low worm-risk paddocks.