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Background
information
Know the important diseases that can occur on your farm, be able to recognise likely symptoms and adopt preventative strategies rather than relying on reactive treatments to suppress disease. Integrate management and chemical treatments to optimise production benefits; minimise residues; rationalise animal health costs; and reduce the development of chemical resistance.
Drench resistance is a major problem in all areas where gastrointestinal parasites occur. Whilst drench resistance is the inevitable outcome of using worm drenches, strategies can be adopted to slow the development of resistance.
Over time, management changes may reduce the risk of disease. In such cases, the underlying program may be changed, for example, to reduce frequency or eliminate treatment. Alternatively, changing flock structure may increase the risk of parasitic disease, and so require more intensive monitoring. If you are unsure, consult your veterinary practitioner, sheep health consultant, or State Department of Agriculture/Primary Industries adviser to determine the likely disease status of your property. Local knowledge from other sheep producers can also help.
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Know and understand the main sheep diseases in your locality
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Use a preventative health program that integrates chemical control and management to prevent disease
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Sheep with good nutrition manage worm burdens better |
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Key decisions, critical actions and benchmarks
Important endemic diseases
The major endemic diseases that require preventative programs include:
- Gastrointestinal parasites, including black scour worm (Trichostrongylus spp), brown stomach worm (Teladorsagia previously known as Ostertagia circumcincta) and barbers pole worm, Haemonchus contortus, (see tool 11.8 and tool 11.9)
- Liver fluke (see tool 11.10)
- Fly strike (see tool 11.11)
- Clostridial diseases and cheesy gland (see tool 11.12).
Implement a preventative health program
Once the risk of disease is identified, adopt cost-effective preventative programs. For worm control the important actions to consider include:
- Strategic treatment timed to reduce the number of drenches required to minimise disease impact
- Management systems to minimise the risk of disease in the highest-risk mobs:
- Grazing management to provide weaner sheep with low-worm-risk
paddocks
- Use ‘smart grazing’ (see Wormboss
http://www.wool.com/Grow_WormBoss_Worm-management_Control-without-drench.htm)
- Rotate sheep and cattle
- Use intensive grazing management to control barbers pole worm
- Make sure weaners and lambing ewes are maintained above
condition score targets to minimise disease risk, and supplement
if falling below critical limits for both energy and protein
- Monitor worm egg counts (WEC) as the basis for when to drench
- Monitor the drench resistance status of your property to ensure only effective drenches are used (see tool 11.9 for guidelines)
- Select sheep for increased resistance to worms (low WEC) and lower dagginess, or purchase rams from studs that can demonstrate progress in this trait without compromising wool and meat quality (see procedure 9.2 in Gain from Genetics)
- Use an integrated parasite management approach.
Trigger points for action
Trigger points are particularly relevant when seasonal conditions are ideal for the development of disease or, alternatively, when drought conditions reduce the necessity for normal strategic treatments. Develop a health monitoring plan that includes trigger points for action.
Signposts  |
View
Worm egg count: for better worm control in sheep – CD, available from Department of Agriculture and Food, WA.
WormBoss – a web-based tool to help sheep producers manage worms in sheep. Visit: www.wormboss.com.au
Integrated parasite management – sheep – information on regional programs is available on the AWI website: http://www.wool.com/Grow_Animal-Health_Integrated-Parasite-Management.htm.
Assessing the economic cost of endemic disease on the profitability of Australian beef cattle and sheep producers – download this technical report from: www.mla.com.au/finalreports
Managing Flystrike - information on managing flystrike can be found on the FlyBoss website at www.flyboss.org.au
Internal Parasites in Prime Lambs interactive CD. Order your copy from MLA by:
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