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Calf Scours – What can be done to prevent it?

Johanna Marsden BVSc MRCVS

Calf scour, or diarrhoea, is one of the biggest causes of poor growth and mortality in calves. An outbreak of infectious scour is costly and has been estimated to cost £57.94 /cow in the herd. It can be prevented with good biosecurity and hygiene. It is important that practical steps are put in place to limit the potential impact scour can have on calves.

The most common causes of scour in the first 3 weeks of life are cryptosporidiosis (parasitic), Rotavirus, Coronavirus (both viral) and E.coli (bacterial). Another parasite coccidia causes scour in calves usually from 3 weeks old and Salmonella at any age. These diseases damage the gut lining, decreasing its ability to absorb nutrients and fluid, leading to watery diarrhoea and dehydration. In complex cases multiple infectious agents are present which can exacerbate the situation. Permanent gut damage can occur and they have a reduced growth rate, increased age of first service and longer finishing rate compared to other healthy animals.

Nutritional scours are less common and there is usually an underlying infectious cause. However, consistency is crucial, feeding milk at the wrong temperature, irregular feeding times or milk replacer at the wrong concentration will cause diarrhoea.

Diagnosing the cause of the scour can be done by your vet with a snap test or fecal egg count, as contrary to popular belief, it cannot be diagnosed by looking at it. Identifying the infectious agent will help with prevention of an outbreak in the future.

Prevention:

Giving calves the best start in life will help protect them from outbreaks of scour. There are 3 key areas where good management intervention will promote healthy young stock.

Colostrum is critical in providing calves with a good immune system to help protect them from infectious disease and to promote growth, setting them up for life. The 6 Q’s of colostrum management should be followed in order to provide this.

  1. Quality – the level of maternal antibodies (IgG) should be greater than 50 g/L. This can be tested easily with a Brix Refractometer where any colostrum less than 22% will be inadequate.
  2. Quantity – they should receive 3L or 10% of their body weight in their first feed.
  3. Quickly – the first feed should be fed within 1-2 hours of birth, with the second feed of the same volume before the calf is 12 hours old.
  4. sQueeky clean – if the colostrum is heavily contaminated with bacteria it will compromise the calf’s immune system due to a reduction in antibody uptake.
  5. Quantifying – total proteins (TP) can be monitored to ensure they have received an adequate amount of good quality colostrum. The blood is tested for the TP should be over 55g/L.
  6. Quietly – they should be fed in a stress-free manor. Stressed calves will have a lower absorption of antibodies.

Housing hygiene is key! Wet, dirty or insufficient bedding will enable pathogens to build up in calving pens, hutches and group/individual pens. Regular cleaning and disinfection will help reduce the burden. Also disinfecting boots and having solid walls between pens will stop transfer of disease between groups of calves.

Vaccination of the pregnant cow will reduce the prevalence of scours where rotavirus, coronavirus or E.coli are an issue on the farm. The calves get the antibodies from the colostrum and will protect them for their first 2-4 weeks of life.

Treatment:

In uncomplicated cases where the calf has a suck reflex:

  1. Isolate the sick calves from the rest of the group.
  2. In the case of Crypto they should be kept separate for at least a week after they have stopped scouring as they will continue to shed the oocysts.
  3. Rehydration with electrolytes
  4. Give 2 extra feeds a day with 2L of water plus a rehydration product containing sodium bicarbonate
  5. Continue feeding milk as normal
  6. With each milk feed add a rehydration product that can be mixed with milk

If the calf has no suck reflex, isolate and call your vet as they will require intravenous fluids. Upon diagnosis of the cause of the scour there are products available to use in an outbreak for Cryptosporiosis and Coccidiosis. Consult your vet to develop the correct treatment plan for your herd.

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