The threat posed by internal parasites is increasing as worm and fluke populations build resistance to drenches. AWI has developed means of addressing the problem through the better use of existing technologies, as well as the development of new products and new methods to diagnose severity.

Internal parasites and scouring

Background

Internal parasites (worms and fluke) are estimated to be costing the Australian sheep industry $369m per year. This cost includes mortalities and production losses (reduced wool cut, stained wool, lowered staple strength), as well as the direct costs of control (mainly drenches and labour).

The impact of internal parasites is undoubtedly escalating. The estimated cost in 1995 was $222m. The reason for this blow-out is drench resistance. Resistance by worms to the 'white' and 'clear' drench groups is long established. Resistance to the newest major drench group, the macrocyclic lactones or MLs (the 'mectins'), is now also wide-spread.

Despite the promise of new drench groups about to reach the market, the problem of selection for resistance remains, thus necessitating the need to use chemicals sparingly in a program which integrates non-chemical parasite management techniques.

AWI is addressing the problems of internal parasites and scouring in three ways:

• Better use of existing technologies 
• New products and practices 
• New diagnostic tests

Better use of existing technologies

Control of worms, lice and flies can be improved in many sheep flocks by applying principles of integrated parasite management (IPM). IPM means that a range of chemical and non-chemical methods are brought together to tackle the parasite problem.

AWI's flagship project in this area is the Integrated Parasite Management - sheep (IPM-s) project. Since 2004, more than $3 million has been invested invested to develop, apply and test IPM systems across a range of wool production environments. There are 23 IPM-s demonstration farms across Australia. Read the IPM section or contact Lewis Kahn for further information.

Another key project is the development of the WormBoss^® package, in collaboration with the CRC for Sheep Industry Innovation. WormBoss is an encyclopaedia of everything you need to know about managing sheep worms. WormBoss is available at the website (click here) and is updated monthly with regional advice.

New products and practices

A range of tools can play a part in the management of worms: oral drenches, capsules, grazing management (such as Smart Grazing), strategic nutrition, and breeding worm-resistant sheep.

AWI continues to invest in research that may lead to new products and practices for the management of worms. AWI and Meat and Livestock Australia (MLA) have jointly invested more than $2.2m in a series of projects that aim to better understand the genetic code of worms and the way they interact with their sheep hosts. While any commercial outcome may be ten years away, the research could ultimately deliver new drenches, vaccines, or other new tools to control worms.

New diagnostic tests

Sheep producers use faecal worm egg counts (FWEC) to determine the size of worm burden being carried by a flock. FWECs are also used to check the effectiveness of drenches. If it is necessary to know what species of worms are present, a larval differentiation test (a dung sample is incubated and the larvae hatching from the eggs identified) is carried out.

These tests are laborious, quite slow and expensive, and not highly accurate. In collaboration with MLA and the Sheep CRC, AWI is investigating new technologies that could make worm diagnosis quicker and more convenient and reliable.

See also: external parasites.