Course: Winter Health | Last Updates: 7th October 2015
Calf scour (diarrhoea) is the most common disease in young calves, accounting for about 50% of all calf deaths.
It can be caused by a number of different organisms, with specific causes dependent on the age of the calf.
For calves four days and younger, scours is usually caused by bacteria such as E coli, salmonella and clostridia. Bacteria can multiply very quickly and therefore impact the calf very quickly.
For calves aged five to seven days the cause can be wider, as it could be bacterial or caused by cryptosporidiosis – a protozoal parasite commonly found in the environment on most farms. Because of the life cycle of the parasite, which tends to peak at 10 days, it only causes scour in calves at least five days old.
Around seven days of age scours tend to be caused by rotavirus, which commonly causes watery diarrhoea in calves, and while coronavirus can also cause scours, it is commonly found in mixed infections.
From 14 days you start to see scours caused by coccidiosis, another protozoal parasite, which can potentially lead to severe impacts on growth rates.
It is worth remembering that scours may not always be caused by infectious organisms.
Calves will sometimes show nutritional scours, which are caused by inconsistency of feeding. This can be minimised by ensuring that milk is always provided in the same way, ie making sure the volume, content, temperature and route of administration (bucket or teat) is the same.
One of the mistakes farmers commonly make is to think that only very young calves are affected by scours, but we are also seeing it in weaned and older calves. This is due to the rumen not being ready for a change in diet from milk to concentrates, and requires a slower weaning process.
How to diagnose and treat it
Calf scours can be easily recognised and it is important it is picked up quickly so that treatment can be administered rapidly to maximise the chance of survival.
By detecting scours early, you should be able to treat it successfully before the illness becomes incredibly serious.
Quite often early signs will include a reluctance to walk, mild colic and a slightly wet tail.
With coccidiosis, where faecal samaples are taken, you can sometimes see a raised faecal egg count – meaning calves are infected, maybe not enough to cause clinical disease, but enough to mean you would not have the weight gain you would expect.
You could also see dehydration or teeth grinding, and with a bacterial infection you often get a higher temperature.
To diagnose what has caused the scours, there are good on-site test kits which can be used. Alternatively you can send samples to a lab to be tested.
It is important to diagnose the cause of the scours to ensure the correct treatment is given and to enable measures to be put in place to minimise the chance of occurrence in the future.
To treat it, fluids, fluids, and lots more fluids are needed to correct the dehydration and acidosis that occurs due to the fluid loss from the calf’s digestive tract.
The old idea of removing the calf from the milk and giving them rehydration therapy alone is out of the window; feed the calf the milk it would usually get, plus additional fluids.
There are a number of different rehydration therapies available, and your vet should be able to advise you on the best product.
In suckled calves, the last thing you want to do is take it away from its mother, but isolating animals affected with scour can reduce the chance of spread to other calves in the group.
If you do isolate, sometimes calves with scours are depressed and cold, so make sure they are out of draughts and near a heat source with plenty of fresh water.
In more serious cases, a vet can put the calf on a drip and administer IV fluids, though this is usually only done on more expensive animals.
How to prevent it
The ket to preventing scours is to provide the calf with a good quality colostrum so it has the antibodies to help fight off the bacterial and virus causes of infection. Most calves require 10% of their birthweight within the first six hours of life.
This spring and summer we have seen more calf scour than usual as colostrum quality has been lower thanks to many cows being nutritionally challenged because feed supplies were low after the bad winter.
In these situations, thinking about nutrition further off is vital. Most colostrum is laid down four to six weeks before calving, so you could make sure you improve nutrition earlier or use colostrum bulkers or replacers to add artificial antibodies. Colostrum replacers are expensive, however – at £30 a dose it might only be worth it for beef calves.
A lot of farmers are checking their colostrum with a colostrometer and then saving and freezing their high-quality stuff for when they have poorer-quality colostrum coming through.
Hygiene and cleanliness are also vital in preventing and controlling calf diarrhoea.
Whatever caused the scours, the route of infection is always the same: either ingestion or inhalation of the organism from an environment which is heavily contaminated by faeces.
Good hygiene must start from the moment a calf is born as many infections are picked up from the calving area, so it is important to keep the calving box clean.
Throughout the weaning period cleanliness must be maintained, so make sure all feed equipment is kept clean, paying particular attention to sick calves by feeding them first and cleaning the equipment before feeding other stock.
Ensure the calf pens are clean, and make sure to properly muck out, disinfect and allow to dry, before bringing a new group into a pen. Straw is more expensive at the moment so people are mucking out less, and we are seeing increased levels of scours as a result.
If you are using a feeding tube for feeding colostrum and one for feeding sick calves, you should also make sure they are labelled clearly to avoid feeding newborn calves with equipment infected by sick calves.
Finally, when moving from different pens of calves make sure to wipe or clean your boots, and make sure any lorries moving calves from pen to pen are properly cleaned and hosed down to remove faeces.
There are vaccines to deal with some of the infectious causes, but it is important to remember that they are very targeted at rotavirus, coronavirus and E coli but do not target salmonella.
There’s a risk that by vaccinating, farmers think they have solved the problem, but you can spend a lot of money and still have scours.
A good regiment of hygiene and management is the best bet, and if you work hard you can get on top of it.
What about in older cows?
Peri-weaning scour is one of the biggest problems facing farmers who wean their calves before they are ready.
It used to be very rare – I first saw it in 1998 and it was five years before I saw it again – but now I see it on two or three farms a year.
It’s caused by rushing the weaning system and changing calves’s diets before their rumens are ready. It causes malnutrition and can be very damaging.
From two weeks old calves should be offered fibre alongside good-quality cake. It has been shown that offering good-quality, 2-3cm chopped straw, on the side of a pelleted starter feed increases solid feed consumption.
Calves should be eating at least 1kg of cake a day/head for at least three or four days before they are weaned.
- Ensure the calf is given good-quality colostrum in the first six hours of life
- Keep the calving area, calf rearing pens and all equipment clean
- Keep and eye out for early signs of scours and take action to treat it immediately
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