Introduction

Where is the Pastoral region?

This region covers the areas across Australia where sheep are run under low rainfall conditions. In central and southern areas, this is generally less than 400 mm annual rainfall, but may be much higher in the northern summer rainfall areas during a very wet season.

In these areas some sheep usually have some worms, but the hot and/or dry conditions keep them at very low numbers and sheep generally tolerate these without the need for drenching. However, under wetter or more crowded conditions worm burdens can become severe, resulting in illness and deaths.

The WormBoss Pastoral region includes these sheep production areas:

• Queensland: north and west of Mitchell, and west of the Great Dividing Range to Hughenden, then west to Julia Creek, then south including Longreach and Charleville, and just including Windorah, Eromanga and Thargomindah in the south-west.
• New South Wales: west of the following towns Goodooga, Nyngan, Lake Cargelligo, Griffith and Finley.
• Victoria: north and west of an approximate line from Swan Hill across to Kaniva.
• South Australia: north of Goyder’s line to the dingo fence.

In some districts within the areas described above (as well as the low rainfall areas of Western Australia, east of the cereal zone), sheep rarely or never need treatment for worms. Low stocking rates help to reduce the worm problem, but these districts also tend to have one or a combination of the following that limits the completion of the worm’s life cycle for much of the time: very seasonal rainfall, extreme heat, high evaporation rates, low humidity, and sparse pastures.

If you are new to these areas, see how much drench your local stock and station agent carries and talk to neighbours and veterinarians to find whether worm problems arise locally and adjust this program accordingly. Also, WormTest regularly while you build your experience in worm management. In the years with above average rainfall, many sheep have died in these areas from worms when local folklore says sheep do not get worms.

The regional boundaries are approximations only due to the seasonal variability, mostly associated with rainfall in this region. A map of the region is shown below.

What worms are covered in this program?

Roundworms

The most important roundworms in this region vary according to latitude and rainfall patterns. In southern areas or when there is winter rainfall:

• Scour worms
  • Black scour worm Trichostrongylus vitrinus / Trichostrongylus colubriformis
  • Small brown stomach worm Teladorsagia (Ostertagia) circumcincta

When there is summer rainfall:

• Barber’s pole worm Haemonchus contortus
• Black scour worm Trichostrongylus vitrinus / Trichostrongylus colubriformis
• Nodule worm Oesophagostomum columbianum

Also important in both the north and south, but mainly for young sheep:

• Thin-necked intestinal worm Nematodirus species

Liver fluke

In this region liver fluke only occurs in imported sheep, except perhaps on irrigated pastures. When sheep are brought here from areas with liver fluke, include a triclabendazole drench (which is effective against all stages of liver fluke) with quarantine treatments for roundworms.

Other gastro-intestinal parasites

Gastro-intestinal parasites of minor (stomach fluke and tapeworm) or occasional (coccidia) importance are not covered in this program.