One of the biggest calf killers in Ireland, north and south, is scour. It is responsible for 40% of calf deaths. A leading cause of scour is Cryptosporidiosis, and the threat is increasing every year.

Cryptosporidiosis is caused by a parasite called cryptosporidium and is usually seen in young calves in their second week. However, calves from five to 35 days old are susceptible.

Regular symptoms of crypto in an infected calf are diarrhoea, dehydration, loss of appetite, fever and abdominal pain.

The infection will cause damage to the gut wall lining, and the calf won’t be able to absorb nutrients.

This leads them to become lethargic, stop drinking and become dehydrated fast. The diarrhoea is notoriously difficult to cure.

There are four species of the cryptosporidium parasite which infect cattle, but cryptosporidium parvum (C. parvum) is particularly common in calves under 6 weeks of age – and it can affect humans.

Calves become infected with C. parvum when they ingest C. parvum oocytes (eggs) which can be found in bedding, pasture, soil and drinking water.

After four days, an infected calf will shed vast quantities of oocytes in their scour. A single calf can spread billions of these eggs, but it only takes ten to cause disease in susceptible calves.


Infection without clinical signs

Even if there are no obvious signs of your animals being infected, you should still be wary of cryptosporidium.

Adult cattle can carry large quantities of the C. parvum parasite, and shed them, despite showing no symptoms of the disease.

6-7 week old calves could still show no clinical signs of infection even though they’re still producing oocytes.

If your calf is suffering from the disease, they should be isolated for a week at minimum once the scouring stops to prevent other animals catching infection from eggs they spread.


The best fix for Cryptosporidium is to stop the disease from being contracted in the first place.

You can reduce the risk of it on your farm through good animal hygiene and animal management; washing dung and faeces from floors, walls and ceilings with an effective disinfectant.

Calving boxes, feeding buckets, boots, and stomach tubes need to be properly cleaned and disinfected too.

When cattle are regularly bedded down it reduces their exposure to faeces – this is a good way to lower the risk too.

Make sure to raise feed and water troughs at least 0.75m off the ground to minimise contamination.

Rehydration for calves is the key to their survival, and 1-2 litres of oral electrolytes 2-4 times a day is recommended.

If you already have infected calves, isolate them immediately from the group; because they spread literally billions of oocytes. They are a massive source of infection.

Administer the drug ‘Halocur’ to the infected calf. It won’t cure the disease but it should help stop your calf from shedding the oocytes and reduce the effects.

There is no point using antibiotics against crypto, and you cannot vaccinate against it. If cryptosporidiosis is a regular occurrence on your farm each year, Halocur can be administered for the first seven days of life as a preventative treatment.

This drug can’t be used on dehydrated animals and can be toxic in the case of an overdose.


If it is at all possible, make sure that all newborn calves get at least three litres or 10% bodyweight of colostrum within two hours of birth to strengthen their immune system.

This will safeguard calves against secondary infections later on, such as rotavirus and coronavirus.

Group calves of similar age together, and don’t overcrowd them. Calves who are a few weeks older could shed the disease, and younger calves have a much less developed immune system.

The best way to ensure your calf gets sufficient colostrum is to be there at calving. Moocall Calving Sensor is the best way to do this.

Because you are alerted an hour and two hours before your calf is on the ground, you can be there to assist the calving, and make sure your calf gets what they need in good time.