Calf scour is one of the biggest health issues in youngstock causing serious financial losses. 70% of farmers have seen scour in calves under six months of age during the previous 12 months and more than 40% of producers have lost animals to the disease over the same period. (1)
Scour can either be nutritional or infectious however we are unable to tell the difference without a laboratory test, this can be achieved with a dung sample and the help of your vet.
Nutritional scour can be due to the components of the milk replacer or the feeding and mixing of the CMR. The cheaper not so high quality milk replacers can contain indigestible vegetable proteins and higher ash levels which usually means higher salt levels. Both the high salt levels and high levels of poorer quality vegetable proteins can cause scour simply due to an osmotic effect in the large intestine, the molecules therefore draw water into the gut lumen resulting in diarrhoea. Badly mixed powder, irregular feeding and inconsistent volumes and temperatures can also result in nutritional upset.
Secondly there is infectious scour, as we know every farm has pathogens. Whether the calves get a disease or not depends on the hygiene, management and immunity of the animal. Rotavirus is the most common cause of scour for calves age 4-14 days. Rotavirus attacks the epithelial cells of the gut lining, the gut villi are then damaged meaning they are no longer able to absorb nutrients, and waters and salts are loss in the form of scour. (2)
The newborn calf is dependent on the antibodies it received via the damns colostrum this protection only last 3 – 4 days therefore it reduces rather than eliminates the risk of Rota Virus. Continued feeding of colostrum/transition milk can extend this period reducing the risk.
The second most common cause of scour is Cryptosporidium this parasite normally infects the calf shortly after birth and causes scour at 5-7 days. Once ingested the parasite attaches to the gut wall and multiplies which causes damage, this then reduces the ability of the calf to digest food leading to watery scour. Cryptosporidium is spread through the oocysts that are secreted in faeces of infected cows or calves contaminating the environment, calves then become infected when they consumed contaminated feed or water.
How to treat scour – remove, rehydrate and continue to feed milk (3)
Remove the calf from the group this will help prevent the spread of infection.
It is important to replace the salts and fluids that are lost due to scour. Give one or two feeds extra feed (2 litres each) of good quality oral rehydration solution.
Continue to feed the milk/milk replacer as this will not prolong or worsen the scour. It will help with the healing of the intestine.
Top tips to avoid scour:
- Calving area should be clean, dry and regularly disinfected
- Calves should receive high quality colostrum (tested with a colostrometer or refractometer) – the calf should receive 10% of its birthweight. Ie – a Holstein calf weighing 40kg should receive 4L of high quality colostrum
- Consistency is key – calves should be fed at the same time, same temperature and volume to minimise nutritional stress
- Fresh starter feed and water to be offered at all times
- Fresh bedding that is regularly cleaned out
- Do not mix older calves with youngers calves, as the older calves may still shed oocysts
- Isolate scouring calves from healthy calves, do not mix them back into the healthy group for at least one week after scouring.
- Ensure good drainage/all drains remain clear as a wet environment raises humidity which can lead to ammonia which is likely to increase the spread of disease between calves
- Keep all calves warm and hydrated particularly if they are still scouring
- Disinfect calf pens before batches and after a disease outbreak
- Clean all equipment – Tubing bags, teats, bottles, buckets, calf coats, overalls, wellies and gates.
- ADAS Report: Economic impact of health and welfare issues in beef cattle and sheep in England (p. 35/36)