internal parasite control in sheep
DESCRIPTION
Internal parasite control in sheep. Fewer worms More dollars. Course aim. Monitor and manage sheep worm populations to improve production, by: Using worm egg counts to detect infestations early. Becoming competent at the faecal egg count test. Regular drench resistance tests. - PowerPoint PPT PresentationTRANSCRIPT
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Internal parasite control in sheep
Fewer worms
More dollars
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Course aim
Monitor and manage sheep worm populations to improve production, by:
1. Using worm egg counts to detect infestations early.
2. Becoming competent at the faecal egg count test.
3. Regular drench resistance tests.
4. Use of WormBoss in decision making.
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Outline
Setting the scene Types of internal parasites Parasite damage to sheep Introduction to WormBoss Worm egg counting Drench resistance
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Setting the scene
Worms cost the Australian sheep industry $369M/yr
This could increase to $700M by 2010
drench resistance
more production losses
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Figure 1. National cost ($million) of major sheep health issues in Australia. (Source: Holmes et al. 2006)
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Types of internal parasites
1. Strongyles or Round worms
2. Cestodes or Tapeworms
3. Trematodes or Liver flukes
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Round worms (Strongyles)
Major cause of production losses in sheep
Summer dominant rainfall Barbers Pole Black Scour
Winter dominant rainfall Brown Stomach Black Scour Lung worms
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Round worms and site of infectionSite Round worm scientific name Round worm common name
Abomasum
Haemonchus contortusTeladorsagia circumcinctaTrichostrongylus axei
Barbers PoleBrown StomachStomach Hair
Small intestine
Trichostrongylus colubriformisTrichostrongylus vitrinusNematodirus spathiger Cooperia curticeiBunostomum trigonocephalumStrongyloides papillosus
Black ScourBlack ScourThin Necked IntestinalSmall IntestinalHook WormStrongyloides
Large intestine
Trichuris ovisOesophagostomum columbianumOesophagostomum venulosumChabertia ovina
Whip WormNodule WormLarge BowelLarge Mouthed Bowel
LungsDictyocaulus filariaMuellerius capillaries
Large LungSmall Lung
(Source: Cole 1980)
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Life cycle of round worms
ADULT
3rd larval stage
2nd larval stage
1st larval stage
EGG
4th larval stage 21 days
Sheep phase
Pasture phase
1-21 days
(Source: Cole 1980)
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Epidemiology
Temperature and moisture are critical for the survival of worm eggs and larvae
Round worms require avg. daily temp. of 10oC and 50% humidity (50 – 75mm) to hatch
Except Barbers Pole – temp. above 15oC
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Tape worms (Cestodes)
Most common/important species Moniezia
live in intestinesno known ill effects
Echinococcus Taenia
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Liver flukes (Trematodes)
Only species in sheep is Fasciola hepatica
Complex life cycle and has a fresh water snail as an intermediate host
Live in bile ducts of liver
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Parasite damage to sheep
Tissue damage Competition for protein Appetite reduction Scouring Anaemia (Barbers Pole)
(Source:www.dpiw.tas.gov.au )
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Overall production effects
Parasites will cause a reduction in: fertility
milking ability
meat production
wool production
wool soundness
immunity
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Introduction to WormBoss
Developed by Sheep CRC and AWI
www.wormboss.com.au
Recommendations: monitor worm populations regular drench resistance tests use non-chemical management strategies if unsure, seek professional advice
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Exercise 1 – Using WormBoss www.wormboss.com.au Select “know your worms” List major summer and winter rainfall
worms Select one worm from each rainfall
group and list its scientific and common name, distribution, location in sheep and affects on sheep
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Worm egg counting
Number of worm eggs in a sample of sheep dung - “eggs per gram” (epg)
Can’t distinguish between different round worm species “strongyle eggs”
More accurate than visual assessment
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Worm egg counting
Useful to decide:
if treatment is necessary
if previous treatments were effective
assess level of worm contamination being put into paddocks
which sheep are worm resistant
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View of worm eggs
(Source: WormBoss website, Dr R Woodgate)
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Worm egg typing
Larval culture and differentiation is required to differentiate between different worm species
(Source: WormBoss website, Dr R Woodgate)
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Exercise 2 – Worm Egg Count Test
Aim of procedure Materials
– including use and care of microscopes
Method Counting Calculations Interpreting results
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Use and care of microscopes Start at lowest magnification Rotate the focus wheel so you know which
direction lowers/raises microscope Focus using coarse focus first, then fine tune Don’t allow microscope head to come in
contact with slide Rest eyes regularly Always clean immediately after use
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WEC test method Weigh 2g faeces from each sample into mixing
bowl Add 60ml of saturated salt solution and mix Pour through strainer to remove course material Stir in a N-S E-W motion before allowing material
to flow into pipette Moisten counting chambers of slide Fill the slide chambers from right to left and with
the slide verandah facing away from operator Allow about 1 min. between preparation and
counting for eggs to float to top of slide
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Counting the faecal eggs See Egg Identification Sheet to identify
different worm egg species
Place slide on microscope with verandah facing away from operator, use fine focus knob to focus slide
Begin counting using lines as a guide
For each sample, count and record number of eggs seen for each species
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Egg identification (page 1)
3. Coccidia
1. Trichostrongylus (Black scour worm)
4. Moniezia (Tapeworm)
2. Haemonchus (Barbers Pole worm)
The images on this page were sourced from:1. www.stanford.edu/class/humbio103/ParaSites2005/Trichostrongyliasis/agent.htm2. www.sheepandgoat.com/HairSheepWorkshop/parasitism.html3. commons.wikimedia.org/wiki/Image:Coccidia.JPG4. www.medata-systems.co.uk
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7. Fasciola (Liver Fluke)
5. Trichuris (Whipworm) 6. Nematodirus (Thin necked Intestinal worm)
9. Dictyocaulus (Lungworm)
The images on this page were sourced from:5. w3.ufsm.br/parasitologia/arquivospagina/ovosdebovinos.htm6. www.stanford.edu/class/humbio103/ParaSites2005/Trichostrongyliasis/agent.htm7. cal.vet.upenn.edu/projects/parasit06/website/lab6.htm8. www.medicalvetonline.com.br/atlas.php
Egg identification (page 2)
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Calculation for FEC test
Number of eggs/gram of faeces =
number of eggs counted x total volume of mix (ml)
volume of counting chamber (ml) x wt of faeces in mix
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Interpretation of FEC test results
www.wormboss.com.au
Click on “Ask the Boss” and read
Click on “Consult the Boss” and follow the prompts
A report will be generated based on the information you enter
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Drench resistance
Essential to know to be able to effectively manage worms
Occurs once worms can survive a dose of a drench that would have previously killed them
Measured by a Faecal Egg Count Reduction Test (FECRT)
Accepted industry definition = a reduction in worm egg count of less than 95%
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Factors influencing development of drench resistance
Chemical group and persistency of the product involved
Frequency of treatments
Worm species involved
Environmental factors
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How common is drench resistance?
Widespread, probably 90% or more of farms have a problem
Sheep worms have evolved resistance fairly quickly to each new drench group
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Drench resistance testing
Essential to know the efficacy of drenches on your property
Assessed through a Faecal Egg Count Reduction Test (FECRT)
Should be conducted every 2 years
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Exercise 3 – Setting up a FECRT
1. Select appropriate sheep − young, wormy and undrenched− at least 12 weeks old
2. Do a worm egg count− collect dung samples from min. 10 sheep− samples tested for enough worm species
(min. 300 epg)
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3. Decide drenches to test − seek professional advice− depends on previous test results and
property drench history
4. Set up test groups− at least 15 sheep in each group plus one
control (undrenched) group− ID each group
Setting up a FECRT
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Setting up a FECRT
5. Drench each group − drench each group with correct drench− make sure:
• no cross contamination of drenches• control group not drenched • correct drenching technique used
6. Return sheep to paddock together
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Setting up a FECRT
7. Collect faecal samples for worm egg counting − 10-14 days after initial treatment collect
10 fresh faecal samples from each group including the control group
− obtain a larval culture and differentiation on samples from each group
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Setting up a FECRT
8. Interpreting results − compare average no. of faecal eggs in
each sheep group with that of the control− Fully effective drench = 95% worm egg
reduction in relation to undrenched control group
% efficacy = (control – treatment) / control x 100
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www.wormboss.com.au