Much of NSW receives non-seasonal rainfall, with increasing summer dominance in the north, and generally a greater tendency to winter dominance in the south of the state. Rainfall is highest in the eastern third of NSW, decreasing to the west.

The three most important sheep worms are barbers pole worm (Haemonchus contortus), black scour worm (Trichostrongylus colubriformis and T.vitrinus) and brown stomach worm (Ostertagia circumcincta).

Mixed infections with these, as well as less important worms, are the norm.

Liver fluke (Fasciola hepatica) can be present in higher rainfall tableland and nearby areas (slopes, coast) and irrigation areas. This can be an important parasite in certain localities and seasons.

Barbers pole worm is the most dangerous worm, and commonly causes problems (anaemia, sudden death) in northern NSW where there is significant summer rainfall.

Black scour worm and brown stomach worm commonly occur in most sheep raising areas of NSW and can cause ill thrift, scouring and death.

Nodule worm (Oesophagostomum columbianum) was once a major parasite of the Northern Tablelands but now occurs rarely if ever in this area. This worm can still be found on the north west slopes and plains, especially in wet summers, and may be of significance to processors because of the effect on quality of sheep intestines ('runners').

A closely related worm, large bowel worm (Oesophagostomum venulosum), occurs commonly in much of NSW but causes few problems.

Tapeworms (Moniezia sp) are common but cause few if any problems and should be ignored.

Occasionally other worms, such as thin-necked intestinal worm (Nematodirus sp) can cause problems, particularly in young sheep.

New South Wales has been divided into four regions for worm management:

Also see:

• WormKill region information
• DrenchPlan region information
• WestWorm region information
• FarWestWorm region information

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 WormKill region information

WormKill is the sheep worm management program for the northern tablelands, nearby slopes, upper Hunter and also coastal areas of NSW where barber's pole worm is commonly a problem.

WormKill is an integrated worm management program combining

• the effective use of drenches
• grazing management
• flock management, including 'early' weaning
• breeding sheep more resistant to worms
• nutrition, and
• 'fine-tuning' based on regular worm egg count monitoring (WormTest) and drench efficacy testing (DrenchRite® or DrenchTest, as well as periodic WormTests after drenching (DrenchCheck)). It is important to get advice from your vet or other qualified adviser.

Important worms in the WormKill region
'WormKill' covers the so-called barber's pole worm-endemic area of northern NSW, where the pattern of summer-rainfall favours this parasite (and also nodule worm, now rare in this area).

The main three worms are barber's pole worm (the most pathogenic), and the 'scour worms', brown stomach worm and black scour worm.

Liver fluke is also an important parasite where conditions favour the intermediate host, a snail.

In this section:

• Barbers Pole worm in the WormKill region
  - Drench and Shift
  - Summer knockdown
  - Shuttle using closantel
  - Shuttle using moxidectin
  - Capsule
• Liver fluke in the WormKill region
• Other strategies for worm control in the WormKill region
• Example of how WormKill may be applied to your property

 Barbers pole worm in the WormKill region

This blood-sucking parasite is perhaps the most important roundworm of sheep (and goats) in the New England region of NSW, nearby areas, and south east Queensland. The narrow spectrum drench closantel, which has persistent activity against susceptible barbers pole worm, and also useful activity against susceptible liver fluke, has been a very important part of the WormKill since its inception in 1984. However, resistance of barbers pole worm to closantel has become widespread since the early to mid 1990s.

A survey by NSW Agriculture and Rural Lands Protection Boards in 1997-1998 showed that closantel is ineffective against barbers pole worm on approximately 50 per cent of farms in the New England region, but this varies from area to area.

On farms where closantel is still effective, the first treatment with this drench is given in late October. This is about the time on the Northern Tablelands when it is warm enough for barbers pole worm eggs to hatch and produce infective larvae on pasture. (Barbers pole worm eggs are more sensitive to cold and desiccation than the eggs of the scour worms).

On the nearby slopes, which are warmer, the 'barbers pole season' may start several weeks earlier.

The timing of subsequent treatments, late December and late February, are based on the periods of protection usually afforded by closantel against susceptible strains of barbers pole worm . These three closantel treatments usually provide protection over the 'barbers pole season', normally late spring to mid-Autumn.

When resistance to closantel begins to appear on a farm, the first indication of this is a reduction in the period of protection provided by the drench. Closantel is normally 99.9 per cent effective against susceptible barbers pole worm for four weeks after drenching.

Barbers worm resistant to closantel

Management of barbers pole worm becomes somewhat more complicated when closantel is no longer effective. It also means that farmers are more likely to resort to the more frequent use of broad-spectrum drenches (as happened before closantel became available in 1982). This results in greater selection for resistance in worms such as black scour and small stomach worms, as well as barbers pole worm.

Some strategies for properties with barbers pole worm resistant to Closantel in the WormKill region:

 Drench and Shift

Drench with an effective broad spectrum drench and/or naphthalophos and move to a fresh paddock.

Low worm risk pastures must be prepared beforehand, particularly for weaners to move to in summer and autumn.

 Summer knockdown

Starting late October, normally four to five treatments of naphthalophos are given at 21 day intervals. Levamisole is an alternative.

To delay resistance to both, use naphthalophos and levamisole in combination.

 Shuttle using closantel

A narrow spectrum drench such as closantel is used (unless resistance to closantel is severe) followed 21 days later by an effective broad-spectrum drench to kill developing larvae.

The broad-spectrum drench can be replaced by naphthalophos (NAP) or a clear (LEV) drench in some situations.

The first of these two drench cycles begins mid to late October, and is repeated nine weeks after the first narrow spectrum drench. At least one of these treatments should include an effective drench to control black scour worm etc.

Example:

Notes:
* only one or two broad-spectrum drenches (to control scour worms) should be required. As NAP has useful if not high activity against scour worms; a broad-spectrum drench may not be needed. Check with WormTest.

** The frequent use of LEV for barber’s pole worm control is only recommended if it is effective against that worm, but ineffective against the scour worms, ie it effectively is a narrow spectrum drench on your farm. Remember there are advantages in using NAP and even LEV in combination with other drenches.

 Shuttle using moxidectin

Moxidectin can be used as the first drench in each cycle rather than closantel.

Moxidectin has sustained action against some species, including barber’s pole worm, so the second drench in the cycle- an effective narrow or mid spectrum drench ie NAP- can be delayed until four weeks after the Moxidectin.

This strategy should be rotated with other treatment options every year.

Example:

Notes:
[1] The time between drenches may be extended depending on the result of WormTests, other control measures, and professional advice.

[2] The product ‘Moxidectin plus Tape’ (moxidectin+praziquantel) does not have a claim for persistent activity against barber’s pole worm.

 Capsule

Capsules containing either albendazole (BZ) or ivermectin (IVM) are available in weaner and adult sizes. A resistance test needs to be done to check the effectiveness of BZs and/or ivermectin before using capsules containing these actives.

Ivermectin capsules should not be used where ivermectin resistance is present but BZ capsules, because of BZ’s different mode of action, can still be used on many farms with moderate BZ resistance. A 'priming' dose of an effective broad-spectrum drench or combination of drenches should be given before the BZ capsule is administered, unless BZ resistance is not present (unlikely). With either capsule, worm egg counts should be monitored throughout the release period of the capsule to ensure that efficacy is as anticipated.

A favoured time for the use of capsules in the New England region is pre-lambing, which often immediately precedes the time of year (October) when conditions are suitable for barbers pole worm. If worms on a farm are susceptible, this treatment prevents or minimises the contamination of lambing paddocks by ewes which may temporarily lose some of their immunity to worms at and soon after lambing. However, as with all anthelmintic treatments, capsules should be used with care and as part of an integrated approach to worm control.

Keep in mind the general rule that, the more heavily worms are suppressed, the greater the selection for drench resistance.

Aim to rotate regularly from one strategy and drench group to another, but do this on the basis of drench efficacy testing and professional advice.

If MLs are used each year, reserve these for the most worm-susceptible sheep, and on just part of your property. A common recommendation is to restrict MLs to just one third of the total number of doses of drench on a farm each year, and not to use MLs on the same part of the farm each year. Others may opt to have 'non-ML' years. Either way, the average frequency of use of MLs per year is reduced.

Note also that if a persistent drench is used, worm egg counts may be low or zero on WormTest one to three months later (depending on the product), even if pasture contamination is high. Further monitoring after this may be required.

 Liver fluke in the WormKill region

If liver fluke is a problem, one to three fluke drenches per year may be required for those mobs that have grazed 'flukey' paddocks.

Some of these treatments may be closantel.

The most important time to give a flukicide is in April/May. At this time, a flukicide effective against all stages of liver fluke is recommended (triclabendazole).

WormTest or blood tests (liver fluke ELISA) can be used to check for liver fluke.

If closantel is not used because of resistance to this drug in barber's pole worm, your liver fluke program will need to be re-evaluated.

Consider the different types of flukicides available to you and if possible avoid using one type of flukicide exclusively. Resistance to flukicides is still uncommon, but this is likely to change.

Non-grazing of fluke-prone areas should also be used to help control liver fluke.

 Other strategies for worm management in the WormKill region

Pre-lambing drench. If indicated by WormTest results, drench ewes with an effective broad-spectrum drench. This can be done when vaccinating ewes two to three weeks pre-lambing for diseases such as pulpy kidney, tetanus, cheesy gland. Remember that healthy dry adult sheep in the WormKill region often do not require broad-spectrum drenches apart from the drench in late December.

Lambs should be given an effective broad-spectrum drench at weaning, 12 to 14 weeks after the start of lambing. After drenching, they should be moved to a low-worm-risk pasture. A second 'drench and move' may also be required at 20 weeks (This may be around late February). Likewise autumn lambs should be drenched at weaning and again - depending on WormTest results - at 20 weeks.

Weaning - 12 to 14 weeks after the start of lambing - is an important part of worm control. It separates the two classes of sheep most susceptible to worms, and it also means that lambs are not competing with their mothers for nutrition. Ewes recover bodyweight faster and are likely to be more productive.

Weaners may need extra drenches in April and/or July. Check with a WormTest.

 Example of how WormKill may be applied to your property

¹ Drenching. These are times when a drench may be required. Timing may change depending on the season. Optimally a WormTest should be done before drenching. Also consider a WormTest after drenching (10 days after for short-acting drenches). DrenchCheck from time to time to monitor efficacy of drench.

In prolonged dry spells or droughts, it is particularly important to do a WormTest before drenching. It is believed that drench resistance develops faster in droughts.

² Grazing Management. For young sheep in particular, aim to move to 'low worm risk' pastures. At least avoid grazing young sheep on pastures likely to be 'wormy' eg lambing paddocks in most cases or pasture previously grazed by young sheep, goats or 'wormy' adult sheep.

³ Extra WormTest. Depending on seasonal conditions, extra monitoring of worm egg counts may be required especially in susceptible stock (young sheep, lactating sheep).

⁴ Barbers pole control. During the barbers pole worm 'season' (roughly November to April in the Northern Tablelands, longer on the slopes and coast), longer-acting drenches or products may be required at times. These include closantel- and moxidectin-based drenches, and ivermectin and BZ capsules. Generally closantel is the first choice, but approximately 60% of farms now have resistance to this drug in the New England. This leaves a mix of some or all of the following: the other longer-acting products, more frequent use of short-acting products, more frequent WormTesting, plus other options including grazing management.

Barbers pole worm eggs require warmth and moisture for development to take place. In the Tablelands, it is generally warm enough from late October. Barbers pole infective larvae on pasture can survive frosts. Larvae tend to die faster in very warm to hot weather.

⁵ Effective broad-spectrum. If using a narrow spectrum drench to control barbers pole worm, a broad-spectrum drench will also be needed at times to control the 'scour worms', principally black scour worm and small brown stomach worm.

⁶ Extra fluke control. If closantel is used for barbers pole worm control, then there will be some, control of liver fluke as well. On fluke-affected farms, additional treatments for fluke may be required. Including any closantel treatments, one to three fluke drenches a year may be needed, depending on the severity of the problem. The most important is the April/May treatment, then the August treatment, then the February treatment. It is best to reserve the most efficient flukicide (usually triclabendazole-based products) for the April-May treatment.

⁷ Late August Pre-lambing. Ewes in good condition, on good feed, and with low worm egg counts should often do not need a drench pre-lambing. Only drench pre-lambing if the indicators suggest ewes will become wormy and heavily contaminate lambing paddocks in subsequent weeks.

⁸ Mid October Marking. Mid October to early November is important as it marks the time when conditions may become suitable for barbers pole worm. Except for preventing a barber's pole worm problem in ensuing weeks, drenching lambs at marking is generally unnecessary. If in doubt, do a WormTest on ewes and lambs just before marking.

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 DrenchPlan region information

DrenchPlan is an 'integrated worm management program' combining:

• the effective use of drenches –the right drench at the right time
• grazing management
• flock management, including 'early' weaning
• breeding sheep more resistant to worms
• nutrition, and
• 'fine-tuning' based on regular worm egg count monitoring (WormTest) and drench efficacy testing (DrenchRite® or DrenchTest, as well as periodic WormTests after drenching (DrenchCheck)).

In this section:

• Right drench, right time
• Other issues in the DrenchPlan region
• Example of how DrenchPlan can be applied to your property

 Right drench, right time

All sheep receive two summer drenches except:

• In dry areas with average annual rainfall 350-500 mm – in these areas the first summer drench in November/December will usually suffice. (Check using WormTest).
• Where sheep have been moved to 'low-worm risk' pastures. (Check using WormTest).
• In all areas where a WormTest in February indicates the second summer drench is unnecessary.

The summer drenches should be effective broad-spectrum drenches:

• The first summer drench is given when pasture is drying off (usually November/December), but no later than mid-December.
• The second summer drench, if required, is given when it is hot and dry (February). Check first with a WormTest.

The summer broad-spectrum drenches are particularly directed at the most important worms in the DrenchPlan areas - black scour worm, and brown stomach worm. Thin-necked intestinal worm can occasionally be a problem, especially in young sheep, and with rain after a prolonged dry spell.

 Other issues in the DrenchPlan region

Barbers pole worm
Barbers pole worm can be a problem in certain areas and seasons. If so, use closantel with either or both of the summer drenches and/or in autumn depending on local conditions and WormTest results. Check that closantel is still effective on your property. Do a resistance test, or least do a WormTest after using closantel. (There should be no barbers pole worm eggs in the faeces of sheep six weeks after treatment with closantel).

Liver fluke
If liver fluke is a problem, one to three fluke drenches per year may be required. The most important of these is the April treatment. At this time, a flukicide effective against all stages of liver fluke is recommended (a triclabendazole-based product). WormTest or blood tests (liver fluke ELISA) can be used to check for liver fluke. Seek professional advice.

Pre-lambing drench. 
If indicated by WormTest results, drench ewes with an effective broad-spectrum drench. This can be done when vaccinating ewes two to three weeks pre-lambing for diseases such as pulpy kidney, tetanus, cheesy gland etc. Remember that healthy dry adult sheep often do not require broad-spectrum drenches apart from the summer drench(es).

Lambs
Lambs should be drenched at weaning, 12-14 weeks after the start of lambing. This may coincide with the first summer drench. After drenching, they should be moved to a 'low-worm' pasture. A second 'drench and move' may also be required at 20 weeks. Likewise autumn lambs should be drenched at weaning and again -depending on WormTest results - at 20 weeks.

Weaners
'Early' weaning - 12-14 weeks after the start of lambing - is an important part of worm control. It separates the two classes of sheep most susceptible to worms, and it also means that lambs are not competing with their mothers for nutrition. Weaners may need extra drenches in April and July. Check with a WormTest.

 Example of how DrenchPlan can be applied to your property

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 WestWorm region information

Broad-spectrum in Spring to young sheep. An effective broad spectrum drench is given to young sheep (less than 18 months old) in October/November.

Closantel drench in Spring. In addition, all sheep receive a closantel drench (if effective) in October/November in the Moree and Narrabri districts each year.

In the Brewarrina, Walgett, Coonamble and Nyngan districts, sheep are drenched with closantel if a WormTest in September/October shows barber's pole worm to be present.

Weaning drench. If weaning does not coincide with the October/November drench, the need for an extra drench at weaning is determined by WormTesting prior to weaning.

WormTest again in late February.

In this section:

• Example of how WestWorm can be applied to your property

 Example of how WestWorm can be applied to your property

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 FarWestWorm region information

There have only been a few cases of drench resistance recorded in the western pastoral districts, however, drench resistance in these areas may be more common than we think.

Sheep producers should be aware of the issue. Consider a quarantine drench when introducing sheep onto your property.

Worms are generally not regarded as a key issue except in good years when rain is persistent and feed is good.

In very good years, and particularly in northern districts (eg Bourke), problems with barber's pole worm, including deaths, can occur quickly and with little prior warning. In wet years, producers should monitor worm egg counts (WormTest) quarterly on lambs/weaners and young ewes/wethers, for example, in the months of February, April, August and November.

Alternatively, time WormTesting just before sheep are to be mustered.

In any case, WormTest 4-6 weeks after significant falls of rain.

Be aware that sharp showers (4 – 10 mm) can cause localised runoff and resultant green feed where sheep will congregate leading to increased worm infestations.