livestock ‘n’ animal health How clean is


Kath Aplin BVSc Cert CHP MRCVS


clean? by Kath Aplin BVSc CHP MRCVS


A more interesting question than it first appears, when you start thinking about it – and the answer (as with so many things) – is “it depends…” It all depends on what it is you’re dealing with, and why it needs to be clean. In a farm environment, cleanliness is vital for controlling the spread of disease, but some things need to be cleaner than others.


Controlling infectious disease is basically a numbers game. Bacteria, viruses and parasites will always be present on farms; whether or not they cause disease depends on whether there are enough of them to overcome the immune system of the animal they come into contact with. The amount required depends on several things: • Particular type of infectious agent – some are more “potent” than others – eg a small dose of Foot & Mouth virus can infect a lot of animals very rapidly, compared to TB, which requires more prolonged contact to spread.


• Route of infection – a cow can eat a fairly large dose of e-coli without getting disease, because her stomach will kill the bacteria, but a tiny amount of e-coli into her teat could easily kill her by causing e-coli mastitis.


• Strength of immune system – a dairy cow producing 50 litres of milk is working hard and her immune system will be under some stress. She will be less able to fight off the same dose of, for example, IBR virus, than a suckler cow.


So the answer to the question “how clean does it need to be?” needs to be answered on a case-by-case basis. A few examples to consider:


A straw yard for calving cows: Considering the points above, we’re dealing with high risk cows – calving is a stressful time which puts the immune system under pressure – and cows teats will be coming into contact with the straw yard. This is never going to be a sterile environment, but the amount of bacteria coming into contact with the cow can be kept to a minimum by always ensuring the surface the cows lie on is visibly clean and dry. Any squelching is a sign of a bacterial soup ready to cause disease.


A cow’s teat when a mastitis tube is being inserted:


Here we’re pushing something inside a cow’s teat, past the natural defence


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mechanisms of the teat end. Visually clean is no longer good enough here – we need to make sure there are no bacteria on the teat end that may get pushed into the teat with the tube. Normal cleaning and drying needs to be followed by scrubbing with an antibacterial wipe.


A field for grazing youngstock This is where cleanliness is difficult to spot. The field may be visually clean, but may be contaminated with parasite eggs. Here you’ll need to know the grazing history of the field to know whether it’s clean or not.


A calf pen following an outbreak of crypto Crypto is present in calf and cow faeces, so removing that faeces by mucking out pens between calves is the most important thing in controlling Crypto. This will remove the vast majority of the parasite, but it’s advisable to disinfect too. It’s important to use a disinfectant that specifically states it’s effective against Crypto – it is resistant to many


disinfectants. Leaving pens clean, dry and empty for a week is enough to kill most bugs, but Crypto can survive for a long time. Unfortunately new calves coming in may bring Crypto with them, picked up from cows (who can carry crypto without showing signs) – so it’s important to keep the calving pen clean too.


It’s not a bad idea to do a review of farm cleanliness every now and then – take an individual look at all areas of the farm, make an assessment of how clean they need to be, how clean they actually are, and what impact that might have on disease. Clean straw is often a better and cheaper disease control measure than veterinary drugs.


Kath has a Certificate in Cattle Health and Production and is a Lantra approved trainer. In addition to cattle medicine she enjoys running practical training courses.


CARLISLE HOUSE, TOWNHEAD ROAD, DALSTON, CARLISLE, CUMBRIA, CA5 7JF TEL (01228 710208) FAX (01228) 711960 E-MAIL vets@paragon.com WEB www.paragonvet.com


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