A New Lifestyle Farmer’s Guide to Fecal Egg Counts (FECs)
What Are Fecal Egg Counts (FECs)?
If you’re managing livestock, you’ve probably heard the term "FECs" tossed around. It stands for Fecal Egg Counts. FECs are a simple way to check how many parasite eggs are lurking in an animal’s poo. This tells you how big a parasite problem you’re dealing with and whether animals need treatment. It’s a handy tool for making smarter decisions about parasite management, keeping your animals healthy, and saving money on unnecessary treatments.
Should you use FECs?
Parasites are a reality of farming life, and ignoring them isn’t an option. They can cause all sorts of issues, like weight loss, anemia, and even death in severe cases. But drenching your animals every time you think they might have worms isn’t the answer either. Blanket drenching can lead to drench-resistant parasites, which is a big problem across New Zealand.
This is where FECs come in. They help you see exactly which animals have a high worm burden, so you can target those individuals instead of treating the whole mob. FECs also let you check if your drench actually worked or if the worms are starting to resist. Plus, they can give you clues about how badly your pastures are infected.
And don’t forget—it’s your job to manage your animals’ health, legally and ethically. FECs make it easier to do that.
The pros and cons of FECs
Pros
FECs can show you which animals need treatment and which don’t, so you’re not wasting money or drench.
By targeting only the high-burden animals, you’re reducing the risk of creating drench-resistant worms.
If the worm count doesn’t drop after drenching, you know there’s an issue to deal with.
High FECs might mean your pasture management needs tweaking to reduce reinfection rates.
You can focus on specific groups like lambs or kids, who might be more vulnerable to worms.
Cons
FECs only show what’s going on at the time of testing. Worm burdens can change fast, so you might need regular checks.
Some worms, like tapeworms, don’t show up well in FECs. You’ll need to watch for other signs too.
Collecting and analyzing samples properly takes a bit of know-how, but it’s easy once you get the hang of it.
If you’re relying on your vet the expense can creep up, especially for larger flocks.
FECs measure the worms in your animals, not the eggs sitting in your paddocks so don’t tell the full story.
Doing Your Own FECs
Your vets will probably be able to carry out FECs for you but that does come at a cost to you. The alternative is to get the equipment and carry out FECs yourself. It's usually easier to buy a complete kit either new or used and it will come with full instructions. But here's a guide to what you'll need.
Essential Equipment
Microscope
A basic light microscope with a magnification of at least 100x is sufficient but you can get very reasonably priced microscopes with a digital display and that can connect to your PC and they make it so much easier.
McMaster Slide or similar
This is the slide you put your sample in and look at under the microscope.
This slide has gridlines that make it easy to count eggs.
A McMaster slide is the standard choice and is widely available. Search online for FEC slide or McMaster slide.
Solution
A saturated salt solution is used to suspend the worm eggs for counting.
You can buy pre-made solutions or mix your own at home using recipes available online.
Sieve or Tea Strainer
Used to filter out large particles like grass and debris from the fecal sample.
Don’t use it for tea afterwards!
Pipette or Dropper
For sucking up the filtered solution and transferring it into the McMaster slide chambers.
Container
A small container, like a plastic cup or a beaker, to mix the feces with the flotation solution.
Something to stir with
For mixing the fecal sample with the flotation solution to create a uniform slurry.
Scales
A small, accurate kitchen or digital scales to weigh fecal samples (usually to 0.1 grams).
Sample Bags or Containers
Use sealable plastic bags or small containers to collect and label fecal samples.
Labels and Marker
For labeling samples with the animal’s ID, collection date, and other relevant information.
Optional (But Useful)
Gloves
Disposable gloves to use during sample collection and handling.
Timer
To ensure you allow enough time for eggs to float to the surface in the solution before counting.
Notebook or spreadsheet
To track results and trends over time for individual animals or groups.
Disinfectant and Cleaning Supplies
For cleaning the equipment after use to prevent contamination between samples.
Once you have these tools, you’re ready to start performing FECs.
The procedure
Depending on your kit, the exact amounts may vary but the general outline of the process is as follows:
Collect Fresh Samples
Grab about a teaspoon of fresh poo from each animal. Put the samples into bags and store them in a cool place and test within 24 hours.
Note: early morning as the animals are waking up is a great time as they generally poo when they first get up.
Make a Slurry
Weigh the appropriate amount of poo and flotation solution (a salty water mix), and stir until it’s well combined. Strain out any big bits using a sieve.
Load a Slide
Fill the chambers of the slide with the liquid mixture, making sure there are no air bubbles.
Count the Eggs
Pop the slide under a microscope and count the eggs in the chambers. Add them up, multiply by the appropriate number, and you’ve got the number of eggs per gram (EPG).
Multiply the number of eggs/gram by the moisture content rating (see below) for a final FEC.
The actual amounts need to be very precise so read the instructions that come with your slides carefully.
Moisture content and why it matters
Here’s something that’s often overlooked: the moisture content of the feces you’re testing can affect your results. Dr. Leo LeJambre at CSIRO in Australia, studied this and found that wetter feces pass through the gut faster, which dilutes the eggs per gram (EPG) in the sample. In short, if you don’t adjust for fecal consistency, your results might not be accurate.
So, how do you account for this? It’s simple: assess and record the consistency of the feces when you collect your sample. Use this easy scale:
Marbles – Dry, hard pellets (normal for healthy sheep or goats, even on lush pasture).
Hand Grenades – Soft marbles clumped together.
Plops – No visible marbles but semi-solid.
Slops – Very soft, almost liquid.
Scours – Fully liquid diarrhea.
Once you’ve rated the sample, adjust your FEC result by multiplying the egg count by the consistency rating. For example, if the feces are rated as "Plops" (3), multiply the raw FEC by 3 to get a corrected value.
Just One Piece of the Puzzle
While FECs are a brilliant tool, they’re not the whole answer. Parasite management is about more than just drenching or testing. You need to look at the bigger picture. Think about your pasture rotation—are you giving paddocks enough rest to reduce reinfection? Are your animals in good condition, or are some more vulnerable to worms? Every farm is different, so understanding your specific conditions is key.
By combining FECs with good pasture management, regular monitoring, and a dose of common sense, you’ll be well on your way to keeping your animals healthy and happy.
Wrapping It Up
Fecal Egg Counts are a useful tool for lifestyle farmers. They help you make smart decisions about drenching, protect your animals’ health, and keeping drench resistance at bay. Yes, it takes a bit of effort to get started, but the benefits are worth it. Pair FECs with a good management plan, and you’ll have happier, healthier animals—and a happier, healthier farm too. Happy farming!
For a more in-depth look at managing your animals' health, enroll on our online courses.
What You Need to Know to Keep Livestock: our online course for lifestyle farmers covering practical, legal and day-to-day animal care.
What You Need to Know to Keep Cattle: a deep dive into understanding cattle and how to keep them happy and healthy.
What You Need to Know to Keep Sheep: from getting set up to day-to-day tasks to shearing - everything you need in one practical course.
What You Need to Know to Keep Goats: goats are great fun but can be tricky to manage. Get ahead of the play with this NZ-focused course.
Pigs Health & Husbandry: this course covers everything you need if you're keeping backyard pigs in New Zealand.
Alpaca Health & Husbandry: an online course where you can learn the essentials about keeping these amazing animals.
