If you were to wander into our kitchen at some point, you may find me sat at the table, looking at cow poo or horse poo through a microscope. Something my dad wishes I’d do elsewhere but since it’s been banned from my bedroom, as that’s where I bake and cook, the only logical place left is the kitchen table!
So, why am I looking at it?
Uncontrolled worm burdens are a big cause for concern in livestock, causing reduced productivity, like growth rates and milk yields, and ill health in the animals, and sometimes even death. Likewise, unnecessary use of anthelmintics (antiparasitic drugs/wormers) is also a big concern, as it can speed up the worm’s resistance to the drugs, so that’s where faecal egg counts come in.
There’s all different types of worms and parasites that can live in livestock, and not all can be seen in an FEC, but many can.
FECs can be done by vets, but you can also learn to do them yourself, like I have, if you have the right equipment.
I use what’s called the McMaster technique (named after the microscope slides you have to use, that are a specific size and have a grid printed on them to help you count the eggs).
I take a sample of the animal’s fresh poo, weigh out a specific amount of it and mix it with what’s called a flotation solution (basically a type of salt water). I then strain it to get all the bits of plant matter out and transfer some of the remaining liquid into one of the special microscope slides. Because the worm eggs are lighter than the flotation solution, they float to the top so are easily seen under the microscope.
I then count the different types of eggs that are inside the grid on the slide and do a calculation that then tells me how many eggs per gram of faeces there are. The result gives you an estimate of how overrun with worms the animal is (the fertile adult female or hermaphrodite worms living in them are who lay the eggs).
The daily output of eggs can vary depending on a number of things, so FECs can’t tell you exactly how many worms are in the animal, but they can give a useful guide to help you decide whether they need treating or not.
It takes some practice to be able to know what you’re looking at and distinguish the different species of worm eggs (and be able to tell eggs from pollen- which is what confused me quite a bit at first).
I find it all so fascinating, which might seem bit strange seeing as we’re talking about cow poo here, but it’s really interesting seeing what’s under the microscope.
We don’t tend to worm our adult cows, as they should have built up a good immunity to worms over time, but I still check a couple of samples just to be sure- especially for anyone who is a bit thin or has another issue. It’s also useful to do another count after worming, to check the level of resistance to the wormer you used.
Faecal Egg Counts are extremely useful in sheep and can be done multiple times throughout the year to track their worm burdens (lambs can be really badly affected by worms), but we don’t have any sheep so for now, I practice on the cows and horses until the day comes when some wooly things return here!