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Home WormBoss Worm Control Program for Goats – East Coast Appendices: Further Information on Goat Worm Control for East Coast Regions

Appendices: Further Information on Goat Worm Control for East Coast Regions

Liver fluke control

Liver fluke control

Liver fluke (Fasciola hepatica) only occurs where the intermediate host (the freshwater snails: Austropeplea (Lymnaea) tomentosa and in warmer areas, Pseudosuccinia (Lymnaea) columella are present. These snails are found where there are slow-moving creeks, swamps, springs or shallow irrigation channels and they can survive in mud when water flow temporarily stops. However, the snail is not necessarily present in all such areas.

Liver fluke may not be present on all paddocks or properties in a ‘flukey’ locality.

Roundworms are often specific to one type of animal, but liver fluke can infect many species including cattle, sheep, goats, alpacas and horses, as well as humans and wild animals.

Prevention

Grazing management can help prevent liver fluke infection. Unfortunately, there is currently no effective method to breed for host resistance to liver fluke.

If liver fluke is present on a property, infection can be prevented or minimised by:

  • fencing the areas that harbour the snail, to keep stock out
  • conducting earthworks to deepen shallow water, or to improve drainage
  • repairing broken pipes and troughs that have resulted in permanent wet areas
  • avoiding grazing of snail-infested areas by the most susceptible animals (sheep, goats, alpacas and young cattle)

Detection

Testing for liver fluke can be done using the dung samples sent for a WormTest. A fluke test, which uses a different method to that used for roundworms, must be specifically requested.

If you don’t know whether your stock are infected with liver fluke, test three times a year (autumn, winter and summer) for at least two years (i.e. 6 tests).

Testing will show whether liver fluke is present and to what extent.

You can also determine which paddocks are affected by testing mobs that have only been run in a particular paddock since the last fluke-treatment.

If fluke egg counts for a particular paddock are frequently high (greater than 25–50 eggs per gram), there may be significant production losses. Reconsider your grazing strategies for the affected paddocks and see if fluke-affected areas can be fenced off.

If results at the three testing times are not always positive, then continue testing at the specified times to decide whether to drench.

If all six tests have been negative and the livers of dead or slaughter animals have not shown any signs of liver fluke, it is likely that the lymnaeid snails are not present on your property to act as a host for liver fluke. In this case, drenching for fluke will not be required (except to remove fluke from animals brought onto the property).

A blood test (antibody [ELISA] test) is also available from various laboratories, for example, the NSW Department of Primary Industries State Veterinary Laboratory at Menangle. Also, a faecal antigen test for fluke is available through Charles Sturt Veterinary Diagnostic Laboratory.

Response

Any positive fluke egg count is significant and indicates treatment is needed.

If testing for two years confirms that stock are infected at all test times, then ongoing testing can be stopped. In this case, three routine treatments for liver fluke should be given to stock that have been grazing the affected paddocks in:

  • April–May
  • August–September
  • February

Some treatments for roundworms (scour worms and barber’s pole worms) will control various stages of liver fluke. Check the label as some are only effective against mature fluke (see Table 1.).

The most important treatment is carried out in April–May and should be based on the flukicide, triclabendazole, which is effective against all stages of the fluke found in the stock. If treatments are also required in August–September and/or February, one or both of these treatments should be a flukicide other than triclabendazole (if this was used in April). This treatment rotation will reduce the rate of development of fluke resistant to triclabendazole.

When bringing in stock from another property, consider including a fluke treatment in the quarantine drench if their fluke status is unknown. Bear in mind that adult liver fluke can live for several years inside host animals (see Table 1).

Table 1. Fluke treatments and the age of fluke from which they are effective

Active Age of fluke killed
Triclabendazole All stages
Albendazole From 12 weeks
Closantel From 8 weeks
Closantel plus oxfendazole* From 6 weeks
Closantel plus albendazole* From 8 weeks
Oxyclozanide plus levamisole From 12 weeks

Source: from Liver fluke disease in sheep and cattle, by J Boray (March 2007) NSW DPI Primefact 446
*No commercial products with this combination are currently available. 
Note: only triclabendazole and albendazole are registered for use in goats.

 

WormBoss worm control program for goats

East coast

 

Table 2. Anthelmintics registered and commercially available for liver fluke control in goats.

Drench
group		 Brand name Active Company WHP
meat
(days)		 ESI
(days)
BZ* Alben Albendazole (19 g/l) Virbac 10 10
BZ* WSD Albendazole Albendazole (19 g/l) WSD 10 10
BZ* Beezed Albendazole (19 g/l) Landmark 10 10
BZ* Valbazen Albendazole (19 g/l) Coopers 10 10
BZ*† Flukare C Triclabendazole (120 g/l) Virbac 21 not set

*MILK: DO NOT USE in lactating animals where milk or milk products may be used for human consumption.

†DO NOT USE less than 21 days before calving, lambing or kidding in cows, ewes or does where milk or milk products from treated animals may be used for human consumption.

Where TRICLABENDAZOLE is accidently given within this period or cows, ewes or does calve, lamb or kid earlier than 21 days after treatment, milk will contain residues. This milk must not be used for human consumption, or supplied for processing for at least 21 days following treatment. Calves fed this milk should not be slaughtered for human consumption within10 days. Lambs or kids fed this milk should not be slaughtered for human consumption within 7 days.

Some BZ drenches containing albendazole are used at slightly increased dose rates to control liver fluke. Dose rates are displayed clearly on the product label.

The following drench actives do not control liver fluke:

  • moxidectin, abamectin or ivermectin
  • oxfendazole and fenbendazole
  • levamisole
  • naphthalophos and pyraclofos
  • monepantel
  • derquantel
  • praziquantel

Resistance to flukicides

Resistance has developed to various flukicides. Rotate between flukicides from different chemical groups, beginning with triclabendazole for the April–May treatment.

More detailed information on liver fluke can be found at the NSW DPI web site:https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0004/114691/liver-fluke-disease-in-sheep-and-cattle.pdf

Roundworm lifecycle and larval survival

Source: Modeled from death rate of the L3 population in ‘Simulation of pasture larval populations of Haemonchus contortus‘ by IA Barger, PR Benyon & WH Southcott. Proceedings of the Australian Society of Animal Production (1972) 9: 38

Factors contributing to paddock contamination with worms

The following table applies to:

Factor Time or conditions Effect
Minimum time before worm eggs can become infective larvae. 4–10 days Short graze periods (less than 4 days) prevent ‘auto-infection’ (animals becoming infected by larvae arising from worm eggs the same mob have recently deposited onto the pasture).
Conditions required for significant numbers of worm eggs to hatch and become infective larvae. 4–10 days of:
Brown stomach worm
Temperature: daily maximum >8°C1
Moisture in this time: >10–15 mm rainfall2
Black scour worm
Temperature: daily maximum >15°C for
T. colubriformis or >12°C for T. vitrinus
Moisture in this time: >10–15 mm rainfall3
Barber’s pole worm
Temperature: daily maximum >18°C1
Moisture in this time: >10–15 mm rainfall3		 Unsuitable conditions prevent eggs hatching and developing into infective larvae.
Note: The eggs of the brown stomach worm are much more tolerant of cold and dry conditions, and in general, grazing management has less effect on its control.
Footnotes: 1Some hatching of worm eggs of all worm species can occur below these daily maximum levels, but this is usually at a small and insignificant rate.
2Brown stomach worm eggs can develop at low rates without rainfall even in a relatively dry faecal pellet.
3Development to infective larvae may occur without rainfall if soil moisture profile is high.
Maximum time worm eggs can live awaiting suitable hatching conditions. Brown stomach worm: 21 days
(Note that some brown stomach worm eggs may survive for longer periods)
Black scour worm: 16 days
Barber’s pole worm: 5 days		 Prolonged periods without the right conditions (temperature/moisture) for egg development will result in the eggs dying. This lowers the worm-risk of paddocks.
However, once hatched, infective larvae of both black scour and brown stomach worm can remain in the faecal pellet until conditions are more suitable.
The time for about 90% of the barber’s pole worm infective larvae (L3s) to die (making paddocks low worm-risk).
Note: larvae of brown stomach worm and black scour worm can survive longer because they can remain in the faecal pellet for extended periods.		 Cold – Maximum temperature: < 15℃
Time for 90% larvae to die: 4 months
Warm – Maximum temperature: about 22℃
Time for 90% larvae to die: 3 months
Hot – Maximum temperature: about 35℃
Time for 90% larvae to die: 1.5 months
Very Hot – Maximum temperature: > 40℃
Time for 90% larvae to die: 1–2 weeks		 L3 larvae do not feed. While waiting to be eaten by animals, they wriggle randomly in drops of moisture, more so in warmer conditions. Increased activity in warm weather depletes their energy reserves faster, hastening death.
In extremely hot, dry and windy conditions the larvae dry out and die.
Minimum time for infective larvae eaten by animals to mature and lay eggs (the ‘pre-patent period’). Sheep: minimum of 18 days for most sheep roundworms.
Goats: minimum of 14 (typically 21) days for barber’s pole worm and 21 days for scour worms.		 Worm larvae eaten by animals soon after an effective drench will take at least 18 days (in sheep) or 14–21 days (in goats) before they can lay eggs. During this period after administering an effective drench, animals are not re-infecting the pasture.

Smart grazing to control scour worms in weaner sheep

NOTE: The research that led to the development of Smart Grazing was conducted with sheep. The basic principles underlying its benefit for reducing the number of worm larvae on pasture will remain the same, but its effectiveness in goats has not been established.

By Norman Anderson & John Larsen, Mackinnon Project, University of Melbourne
Source: Mackinnon Project website (10 December 2011)

Introduction

Smart grazing is an improved, yet simple and reliable strategy for the control of worms in weaner sheep during their first winter. It can counter the negative effects of summer rainfall that reduces the effectiveness of the ‘2-summer treatment strategy’ in the winter rainfall areas of southern Australia.

The why and how of ‘Smart grazing’

Merino weaners are very susceptible to worms in their first winter. Consequently, they need to graze pastures that have as few worm larvae as is practicable. ‘Smart grazing’ combines intensive grazing for 30 days with each of the 2 ‘summer’ drenches to ensure that virtually no worm eggs are deposited on a chosen pasture from the first summer drench (November) until after the autumn break (March–April), when the weaners are put into these pastures.

Intensive grazing means using 2½–3 times the normal stocking rate for no longer than 30 days after each of the summer drenches are given. After the intensive grazing period, the paddocks are de-stocked to allow the pastures to re-grow. This means that the total stocking pressure for the ‘Smart grazed’ paddock will be the same as that for a paddock continuously stocked at the farms normal stocking rate.

The intensive grazing will reduce pasture residues to around 800–1000 kg DM/ha after the first summer drench, and around 600 kg DM/ha after the second. If there is insufficient feed, the periods of intensive grazing can be reduced. On the other hand, if there is excess feed the summer drenches can be ‘staggered’ for different mobs so as to provide a longer intensive grazing period or cattle can be used as well.

Finally, the weaners must be drenched with an effective drench before they start grazing the ‘Smart grazed’ paddock after the autumn break.

Smart grazing on a typical farm

A typical self-replacing flock of 5,000 DSEs in southern Australia is made up of 1,500 ewes, 1,500 wethers and 1,000 weaners, running at a winter stocking rate of 15 DSE/ha.

70 ha of ‘Smart grazed’ paddocks must therefore be prepared for the weaners. Thus, 2600 DSE (70 x 15 x 2.5) are needed to stock the 70 ha at 2½ times the normal stocking rate for each of the two intensive grazing periods—this uses all of the wethers and 70% of the ewes on the farm.

A timetable for ‘Smart grazing’

OCTOBER: Select the ‘Smart grazing’ paddock—choose one with a history of good winter pasture.
NOVEMBER: Give the first summer drench (this must be an effective product), then intensively graze the paddock at 2½–3 times the normal stocking rate.
DECEMBER: Remove the sheep to another part of the farm after 30 days intensive grazing. Ideally, the pasture residue should be 800–1000 kg DM/ha (2–3 cm in height).
JANUARY: Paddock remains unstocked until the second summer drench.
FEBRUARY: Give the second summer drench, then intensively graze the ‘Smart grazing’ paddock with the drenched sheep (again, not for greater than 30 days).
MARCH: Paddock remains de-stocked until the autumn break.
AUTUMN BREAK (MARCH–APRIL): Drench weaners and set-stock on the ‘Smart grazing’ paddock when pasture is greater than 600 kg DM/ha (1.5 cm). Weaners can remain there until spring but monitor their worm egg counts every 4–6 weeks.

Why does smart grazing work?

The intensive grazing periods:

  • Reduce the amount of pasture dry matter, making the pasture less suitable for the survival of worm larvae.
  • Ensure that there is no deposition of worm eggs on the pasture from the time of the first summer drench until the autumn break.
  • Probably allow the drenched sheep to ‘vacuum’ up infective larvae in much the same way as cattle do when they are used in alternate grazing programs with sheep.
  • Have the same cumulative stocking pressure from November to March as set-stocked paddocks grazed continuously by wethers.
  • Are quite flexible. What must not be changed is the need (i) not to exceed 30 days grazing after each summer drench, and (ii) for a fully-effective product to be used at the summer drenches.

What are the benefits?

Results from a controlled experiment over 2 years in western Victoria show that, compared to weaners grazing paddocks prepared the usual way (grazed by wethers over the summer/early autumn), weaners grazing ‘Smart grazing’ plots:

  • grew 13% more clean wool (2.29 vs. 2.03 kg) which was 3.5% broader (17.1µ vs. 16.5µ)
  • were 3 kg heavier in October (46.5 vs. 43.2 kg).

During winter, the egg counts from the ‘Smart grazed’ weaners didn’t go higher than 250 epg, a trigger for drenching weaners used by many farmers and their advisers. In contrast, the weaners on the paddocks prepared by set-stocked wethers exceeded 400 epg in both years.

The numbers of worm larvae on the ‘Smart grazed’ pastures in winter were from one-half to a one-third of those on pastures in paddocks prepared by grazing with set-stocked wethers.

Smart grazing to control barber’s pole worm in lambing ewes

NOTE: The research that led to the development of Smart Grazing was conducted with sheep. The basic principles underlying its benefit for reducing the number of worm larvae on pasture will remain the same but its effectiveness in goats has not been established.

‘Smart grazing’ is a system developed in Victoria by Dr Paul Niven to create low worm-risk autumn weaner paddocks in winter rainfall regions. This was adapted for the Northern Tablelands of NSW by Dr Justin Bailey, and is called ‘Smart Grazing—summer rainfall’. Both versions are based on very short periods of intensive grazing at increased stocking rates.

The Northern Tablelands version takes advantage of a four-month cold period in winter (May-August) combined with two bursts of intensive grazing in summer and autumn. This results in an eight-month period where contamination of the paddock with worm eggs is prevented and most of the existing eggs and larvae die.

The process uses a high stocking rate during the grazing period, about four times normal, in order to rapidly reduce the pasture mass, thus increasing exposure of worm larvae to the elements to increase death rate.

The success also relies on the sheep used for grazing being treated with a fully effective drench and that they only graze the paddocks within the protection period of that drench.

Steps for ‘Smart grazing—summer rainfall’

  1. January/February: Graze the lambing paddock with sheep immediately after they have been treated with an effective short-acting drench and graze for no longer than three weeks after that drench. Stock at 3–4 times the normal stocking rate in order to reduce the herbage mass to about 1000 kg DM/ha (or about 3 cm in height).
  2. March/April: Repeat step 1.
  3. May, June, July and August:
  • In cold, tableland districts, when the mean daily maximum temperatures are consistently below 18°C, these paddocks can be grazed by any stock as it is too cold for the eggs of the major worm parasites, barber’s pole and black scour worms, to hatch to infective larvae.
  • In warmer areas adjacent to the tablelands, this cold period will be shorter and Step 3 (from above) may be restricted to June and July. Review your local climate history (see Find your ‘cold period’) to find when the temperatures over a week will have daily maximums below 18°C.
  • In hotter areas, where the mean daily maximum temperatures are higher than 18°C, or below it for only days or a few weeks, step 1 can be repeated.

Drench groups and actives

When using anthelmintic products in goats, a veterinary prescription is often required because: 

  • Goats require a different dose rate and withholding period than specified on most products, even for many registered goat drenches.
  • Most sheep drenches are useful, but not registered for use in goats.

While cattle drenches can be used at the label rates on goats in South Australia and sheep drenches on goats in Victoria, a veterinary prescription is still required for dose rates recommended for goats.

(Click here for the Paraboss Products Search Tool)
Drench groups and actives Worms Examples* of brand names/comments
BZ or benzimidazole group (‘white’)B
albendazole
fenbendazole
oxfendazole		 barber’s pole worm, ‘scour worms’, adult liver fluke, nodule worm.
Aids control of intestinal tapeworm (Moniezia)		 Albendazole: Alben, Valbazen, WSD Albendazole
Fenbendazole:
Beezed, Panacur 25, Oxfendazole:
Beezed LV, Oxfen LV
LV or levamisole group (‘clear’)B
morantel
levamisole		 barber’s pole worm, ‘scour worms’, nodule worm Morantel: Oralject
Levamisole: None registered
ML or macrocyclic lactone groupB (sometimes called ‘mectins’)
ivermectin
abamectin
moxidectin		 barber’s pole worm, ‘scour worms’, nodule worm Abamectin: Virbamec
Ivermectin: None registered
Moxidectin: None registered
AAD or amino-acetonitrile derivative groupB
monepantel		 barber’s pole worm, ‘scour worms’ None registered
SI or spiroindole groupM
derquantel		 barber’s pole worm, ‘scour worms’, nodule worm None registered
OP or organophosphate groupM
naphthalophos (NAP)
(OPs have lower or variable efficacy against ‘scour worms’ in the upper GIT and immature barber’s pole worm)		 barber’s pole worm, ‘scour worms’ None registered
TZ or benzimidazole group (flukicide)N
triclabendazole		 Liver fluke (all stages); not effective against round worms Triclabendazole: Flukare C, Fasinec, Exifluke
SA or salicylanilides/phenols groupN
closantel		 Liver fluke (> 9 weeks and adult) and barber’s pole worm None registered
IQ or isoquinolone groupN
praziquantel		 Intestinal tapeworm (Moniezia) None registered

*These are all of the commercial anthelmintics registered and commercially available for goats at June 2023. In most states of Australia, sheep drenches can be used in goats with an off-label veterinary prescription. 

Breadth of activity across different worm species: BBroad-spectrum; MMid-spectrum; NNarrow-spectrum

Actives: An ‘active’ is the chemical in a drench responsible for killing worms. Some drenches have more than one active and are called ‘multi-active’ or ‘combination’ drenches.

Combination or multi-active treatments: Proprietary treatments containing more than one active. Formulated to be compatible as a mixture. Note: Do not mix your own drenches unless the labels state that you can.

Product formulation: All single actives are available as oral drenches. Moxidectin is also available in injectable products. Moxidectin is not registered for use in goats and an off-label prescription is required from your veterinarian. Pour-on products should not be used in goats for worm control.

Length of protection: Varies from short-acting (‘knock-down’ that kills susceptible worms within the animal) to mid-length (1–6 weeks) and long-acting (approx. 3 months), which not only kill susceptible worms already in the animals, but also infective larvae that the goats eat during the protection period.

‘Scour worms’: Mainly black scour worm and (small) brown stomach worm, but also others.

Label: Check product labels for full details. Follow the label or veterinarian’s instructions.

Using sheep drenches in goats: Veterinarians can prescribe sheep drenches for goats, but must provide written details of withholding periods and dose rates.

Other parasites: Drench groups and actives shows effectiveness of groups against other parasites of minor importance.

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