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Internal parasite control in sheep

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Presentation on theme: "Internal parasite control in sheep"— Presentation transcript:

1 Internal parasite control in sheep
Fewer worms More dollars

2 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. Use of WormBoss in decision making.

3 Outline Setting the scene Types of internal parasites
Parasite damage to sheep Introduction to WormBoss Worm egg counting Drench resistance

4 Setting the scene Worms cost the Australian sheep industry $369M/yr
This could increase to $700M by 2010 drench resistance more production losses

5 Figure 1. National cost ($million) of major sheep health issues in Australia. (Source: Holmes et al. 2006)

6 Types of internal parasites
Strongyles or Round worms Cestodes or Tapeworms Trematodes or Liver flukes

7 Round worms (Strongyles)
Major cause of production losses in sheep Summer dominant rainfall Barbers Pole Black Scour Winter dominant rainfall Brown Stomach Lung worms

8 Round worms and site of infection
Round worm scientific name Round worm common name Abomasum Haemonchus contortus Teladorsagia circumcincta Trichostrongylus axei Barbers Pole Brown Stomach Stomach Hair Small intestine Trichostrongylus colubriformis Trichostrongylus vitrinus Nematodirus spathiger Cooperia curticei Bunostomum trigonocephalum Strongyloides papillosus Black Scour Thin Necked Intestinal Small Intestinal Hook Worm Strongyloides Large intestine Trichuris ovis Oesophagostomum columbianum Oesophagostomum venulosum Chabertia ovina Whip Worm Nodule Worm Large Bowel Large Mouthed Bowel Lungs Dictyocaulus filaria Muellerius capillaries Large Lung Small Lung (Source: Cole 1980)

9 Life cycle of round worms
(Source: Cole 1980)

10 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

11 Tape worms (Cestodes) Most common/important species Moniezia
live in intestines no known ill effects Echinococcus Taenia

12 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

13 Parasite damage to sheep
Tissue damage Competition for protein Appetite reduction Scouring Anaemia (Barbers Pole) (Source: )

14 Overall production effects
Parasites will cause a reduction in: fertility milking ability meat production wool production wool soundness immunity

15 Introduction to WormBoss
Developed by Sheep CRC and AWI Recommendations: monitor worm populations regular drench resistance tests use non-chemical management strategies if unsure, seek professional advice

16 Exercise 1 – Using WormBoss
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

17 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

18 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

19 View of worm eggs (Source: WormBoss website, Dr R Woodgate)

20 Worm egg typing Larval culture and differentiation is required to differentiate between different worm species (Source: WormBoss website, Dr R Woodgate)

21 Exercise 2 – Worm Egg Count Test
Aim of procedure Materials including use and care of microscopes Method Counting Calculations Interpreting results

22 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

23 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

24 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

25 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. 2. 3. 4.

26 Egg identification (page 2)
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. 6. 7. 8.

27 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

28 Interpretation of FEC test results
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

29 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%

30 Factors influencing development of drench resistance
Chemical group and persistency of the product involved Frequency of treatments Worm species involved Environmental factors

31 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

32 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

33 Exercise 3 – Setting up a FECRT
Select appropriate sheep young, wormy and undrenched at least 12 weeks old Do a worm egg count collect dung samples from min. 10 sheep samples tested for enough worm species (min. 300 epg)

34 Setting up a FECRT Decide drenches to test Set up test groups
seek professional advice depends on previous test results and property drench history Set up test groups at least 15 sheep in each group plus one control (undrenched) group ID each group

35 Setting up a FECRT Drench each group Return sheep to paddock together
drench each group with correct drench make sure: no cross contamination of drenches control group not drenched correct drenching technique used Return sheep to paddock together

36 Setting up a FECRT 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

37 Setting up a FECRT 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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