I remember standing in a muddy field back in ’94, watching a vet explain why my best heifers were looking hollow-eyed and flagging, while I was busy pouring money into every drench the salesman had ever promised would work. The truth is, most people think parasite control is about buying the most expensive bottle on the shelf, but they’re just flushing cash into the pasture. If you don’t actually know what’s living in those guts, you aren’t managing a herd; you’re just gambling with your margins. Learning how to run faecal egg counts isn’t some fancy laboratory trick for academics—it’s the only way to stop guessing and start seeing exactly what your livestock are actually dealing with before the weight loss hits your bottom line.
In this guide, I’m stripping away the marketing fluff to show you the practical reality of the process. I’ll walk you through the kit you actually need, how to collect samples without making a mess of your day, and more importantly, how to read the results so you don’t waste a penny on unnecessary treatments.
Table of Contents
Guide Overview
Tools & Supplies
- Microscope (Compound light microscope with 10x and 40x objectives)
- Centrifuge (To separate eggs from fecal matter)
- Pipettes (For precise liquid measurement)
- Counting Chamber (McMaster slide or similar)
- Fecal samples (Freshly collected)
- Fecal flotation solution (e.g., saturated salt or sugar solution)
- Distilled water (For dilution and cleaning)
- Microscope slides and coverslips (Bulk pack)
- Collection bags and labels (For sample storage)
Step-by-Step Instructions
- 1. First, you need to pick the right animals to sample, and no, you don’t just grab the first three sheep you see by the gate. You want the ones that actually matter—the ones that are eating the most grass but aren’t putting on the weight they should be. I usually go for a group of about ten to fifteen animals from a single paddock to get a representative idea of what’s happening in that specific bit of ground.
- 2. Timing is everything, and if you’re doing this in the middle of a drought when the grass is nothing but dust, you’re wasting your time. You want to catch the parasite load when the conditions are right for them to thrive, typically when the ground is damp and the grass is actually growing. If you sample when the animals are already looking hollow-eyed and ribby, you’ve missed the window to save any real money.
- 3. Now, for the collection itself, you’ll need a clean bucket and a way to keep the samples from drying out. Don’t go grabbing a handful of dung from the surface where the sun has been baking it; you want a fresh, moist sample from the middle of the deposit. If it’s dried out, the eggs die or become impossible to count, and you’ll end up paying a lab to tell you absolutely nothing useful.
- 4. You can’t just throw all the dung into one giant bucket and call it a day. You need to take individual samples from several different animals—at least five or six—and put them into separate, labelled bags. If you mix them all together, you’re looking at an average that tells you nothing about which specific animal is the “super-spreader” currently draining your profit margins.
- 5. Label those bags like your life depends on it. Write down the date, the animal’s ID, the paddock they came from, and the breed. I’ve seen plenty of lads send samples off only to get a report back three days later that’s completely useless because they couldn’t remember which group of ewes the dung came from.
- 6. Once you’ve got your samples bagged and labelled, get them to the lab immediately. You can try to be clever and do it yourself with a microscope in the kitchen, but unless you’ve spent years looking at microscopic larvae, you’ll just be guessing at the numbers. It’s better to pay a professional a few quid to give you a hard number than to spend a fortune on a drench that the worms have already learned to ignore.
Understanding How to Run Faecal Egg Counts

Now, don’t go thinking a single sample from one animal tells you the story of the whole field. If you take a scoop of dung from a sheep that’s been standing in the dry corner of the paddock, you’re going to get a result that makes you feel far more confident than you actually should be. You need a proper parasite burden assessment, which means taking samples from several different animals across different parts of the grazing area. If you only test the one animal that looks a bit dull, you’re just confirming what you already suspect; you want to know what the entire herd is up against before you start pulling the trigger on expensive drenches.
When you get into the actual lab work, most of us are looking at the McMaster technique procedure because it’s the standard for a reason—it gives you a number you can actually use. You aren’t just looking for “worms”; you’re looking for an eggs per gram calculation that tells you if you’re dealing with a manageable nuisance or a slow-motion disaster. If the count is low, you might just hold off. But if that number climbs, you know you’ve got a problem that’s going to cost you more in lost weight and poor condition than any bottle of medicine ever will.
Key Things to Know

Now, don’t go thinking a single sample tells you the whole story. If you grab a handful of dung from one animal and decide the whole herd needs a drench, you’re likely making a mistake that’ll cost you a week’s profit. Parasites don’t distribute themselves evenly across a field; you’ll have one cow carrying a massive load while the one standing next to her is clean as a whistle. You need a representative sample—a handful of animals from different parts of the pasture—to get a true parasite burden assessment. If you’re just testing the easiest animal to catch, you’re not doing science, you’re just guessing.
When you’re looking at the results, don’t get bogged down in the fancy jargon the lab uses. Whether you’re using a professional service or attempting a basic McMaster technique procedure yourself, the only number that actually matters is the eggs per gram calculation. That number tells you if you’re dealing with a manageable nuisance or a quiet catastrophe in the making. I’ve seen plenty of men chase their tails with expensive drenches when all they really needed was to get the stock off the wet ground and let the grass recover.
Five ways to stop throwing money at the worm problem
- Don’t just sample the easy animals. If you only take dung from the ones that look healthy and easy to catch, you’re lying to yourself. You need to get a representative mix—the ones looking a bit dull, the ones in the wetter ground, and the ones that look fine—or you’ll end up treating the whole lot for a problem that might only be affecting a handful.
- Timing isn’t a suggestion; it’s the difference between a working plan and a wasted morning. If you wait until the sheep are already flagging and losing condition, you aren’t managing a parasite load, you’re just performing an autopsy on your profit margins. Get the samples in when the grass is growing and the animals are still holding their weight.
- Stop treating the whole herd based on a single sample. I’ve seen too many folk see one high count and immediately go for the big bottle of drenches for every animal in the field. That’s how you breed resistance, and once those worms learn how to live with your chemicals, you’re well and truly finished. Use the count to target, not to blanket.
- Watch the weather as much as the results. If we’ve had a wet, mild spring, those egg counts are going to tell a different story than they would during a dry spell. A high count in a damp year means you need to be on top of it immediately, whereas a dry year might give you a bit more breathing room to plan.
- Keep a paper trail that actually means something. Don’t just file the lab results in a drawer and forget them. I keep mine tied to the specific field and the specific group of animals. If you can’t look back at last year’s numbers and see a pattern, you aren’t running a farm, you’re just playing a guessing game with your bank balance.
The Bottom Line on Worm Counts
Stop treating your whole herd based on a feeling; if you aren’t running actual counts, you’re just paying a chemist to help you build up resistance for nothing.
The goal isn’t a zero count—that’s impossible and expensive—it’s about knowing exactly which animals are the heavy lifters and which ones are just eating your profit.
A piece of paper with a number on it is useless unless it changes what you do in the field; use the data to decide when to move them or when to hold off on the drench.
Bottom Line and Beyond

At the end of the day, running a faecal egg count isn’t about following some fancy laboratory protocol to impress the neighbors; it’s about knowing exactly what is happening in your pasture before it starts eating your margins. You’ve seen the steps: collect the samples properly, don’t let them sit in the sun, and for heaven’s sake, don’t just guess which worm is doing the damage. If you treat every animal with a heavy-duty drench because you saw a colorful advert in a magazine, you aren’t farming; you’re just subsidizing the parasite population and building resistance that will haunt you for a decade. It comes down to the numbers—if the count is low, leave the medicine in the shed and let the grass do the work.
I’ve spent forty years watching people chase the latest “miracle” product, only to find themselves staring at a field of thin, lethargic stock and an empty bank account. This isn’t about being a scientist; it’s about being a practical steward of your land and your livestock. If you take the time to understand the parasite load in your specific soil and rainfall, you stop reacting to problems and start managing them. It’s a bit more legwork and a bit more patience, but I’d much rather spend an afternoon collecting samples than a winter trying to figure out where the profit went.
Frequently Asked Questions
How much is this actually going to cost me per head compared to just treating the whole lot?
It’s a simple bit of math, though most people skip the arithmetic until they’re looking at a dry bank account. Treating the whole lot is what we call “blanket dosing,” and it’s the fastest way to turn your profit into worm resistance. A proper egg count might cost you a few quid per sample, but compared to the price of a full drenching regime and the cost of losing a calf to a heavy worm load? The count pays for itself before the cheque even clears.
If the count comes back high, do I drench the whole herd or just the ones looking a bit peaked?
If the count’s high, don’t just go grabbing the drenching gun and hitting every head in the field. That’s how you breed worms that don’t care about your chemicals. If you’ve got a few looking peaked or losing condition, treat them, but ideally, you want to be targeting the high-shedders. It’s about precision, not a blanket approach. Treat the heavy hitters, keep the rest on pasture, and stop throwing money at the whole herd just because you’re worried.
How do I know if the results are actually accurate, or if the lab has just handed me a pile of useless numbers?
Look, a lab report is just a piece of paper until you check the math against the field. If they send back a number that looks wildly different from what you saw in the yard last year, don’t just nod and pay the invoice. Check your sampling method first—if you didn’t mix the dung well or you only sampled the dry patches, the numbers are rubbish. If the results don’t match the animal’s condition, call them out.




































