Faecal Worm Egg Count In Sheep, Cattle and Horses. Presenter: Andrew Cosby Elisabeth Murdoch College. Vic President Victorian Association of Agricultural and Horticultural Educators.
Reasons for Undertaking a Faecal Worm Egg Counts Allows the farmer to decide when to drench his sheep, cattle. Results in less drench used throughout the year as it prevents drenching when not required. Reduces the incidence of worm resistance in sheep or cattle
Reasons for Undertaking a Faecal Worm Egg Count by Students. It is easy to perform. Students get to use microscopes on more than one occasion Students get to see worm eggs and apply the results in a real context. Allows for discussion of resistance in worms and overuse of drenches.
Materials- ~ 100ml beaker (Figure 3) ~ pipette ~ microscope (figure1) ~ Whitlock Universal counting slide*(figure2) or equivalent called Chalex Figure 1 ~ bucket ~ weigh scales ~ spatula ~ sieve (small) ~ rubber gloves ~ saturated salt solution ~ 10ml syringe ~ plastic cup ~ whisk Figure 2 Figure 3
NOTE: Rubber gloves should be worn!!! Step #1 Collect a faeces sample from a sheep. At least five pellets. This can be taken two ways. Option 1. Take straight from the sheep Option 2. Wait for it to defecate. May take some time. Step #2 Weigh out 2 grams of the sample into a plastic cup.
Step #3 Using a 10ml syringe or 10ml measuring cylinder add 10ml of water to the faeces you just weighed out. Step #4 Mix faeces and water to a consistent mix resulting in minimal lumps.
Step #5 Add 50ml of saturated salt solution* to the thin paste and mix well. If you do not mix it well enough it can result in a false count. Step #6 Having mixed the sample thoroughly pour the mixture through a small sieve into a second clean beaker. This will remove the large pieces of material.
Step #7 Stir vigorously using a pipette the filtered mixture once more. Make sure you stir back and forth as stirring in a circular motion will throw the eggs into the centre and can result in a false count.
Saturated salt solution- ~ Poor bag of salt* into a clean bucket and fill ¾ full with cold water. ~ Give it a good stir using a whisk before leaving it to sit for about 10 minutes. ~ Using a syringe draw up 10ml of the solution. ~ Place a beaker on the scales and zero them ~ Squirt the solution in the beaker, it has to way as close to 12 grams as possible (anything above 11.8g is fine). ~ If you are struggling to get it to weigh 12g give it a good stir or add more salt. ~ Make sure your scales are accurate!!! *normal 2kg bag of sea salt from the supermarket, even Home Brand! Back to steps
Step #8 Draw up a sample, using either a pipette or a syringe (whatever is easier). Step #9 Squirt the sample into the 2 middle cells of the Whitlock Universal Counting slide.
Step #10 Place the slide under the microscope and set up microscope to suit. When focusing use the x10 objective and focus on the air bubbles. The eggs float to the top of the slide where air bubbles are. Step #11 Count all the eggs between the ruled lines in both cells of the slide if using the Chalex slide or one cell if using the Whitlock slide
Egg types- The main types of parasite eggs that can be found in sheep faeces include nematodes, trematodes and cestodes. ~Nematode species include: -Trichuris (fig 1) -Strongyle type worms* (fig 2) *group of species not actual species ~ Cestode species include: -Tapeworm (fig 4) ~Trematode species include: -Fluke (fig 5)
Step #12 Calculate faecal egg count. To find out how many eggs per gram you use the formula below: epg= eggs counted x 30 This is the formula because the 2gram sub-sample was diluted to 60ml. So a ratio of 1:30 weight/volume was created. Each cell on the slide holds 0.5ml of the mix.
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To purchase the Whitlock Universal Counting Slide see details below. JA Whitlock & Co PO Box 51, EASTWOOD NSW 2122, AUSTRALIA ABN 70 033 804 404-GST Registered phone (02) 9638 1142 fax : (02) 9638 1131 e-mail slides@whitlock.com.au website www.whitlock.com.au Back to materials list