Spring born calves and lambs face coccidiosis threat

Thanks to antibodies gained through ingesting colostrum early in life, calves and lambs initially acquire some passive immunity to the parasite. But this protection is short-lived, leaving young animals particularly susceptible to infection as they grow and develop as the weather warms up.

In spring born calves disease can occur at any age from three weeks to six months old and in lambs, maternal immunity wanes at four to eight weeks of age.

Cinical coccidiosis is caused by a build-up in the rearing environment of oocysts produced by the Eimeria parasite.

Susceptible growing calves and lambs become infected by ingesting these oocytes when they lick contaminated objects in their rearing environment or ingest feed or water contaminated by faeces. Once taken into the body in sufficient numbers, the oocysts hatch and the parasites invade and destroy intestinal cells. Infection often leads to diarrhoea, weight loss and poor growth rates.

Alongside good hygiene practices, anticoccidial treatments often have to be used strategically to manage the disease threat on many cattle and sheep units as a consequence.

This allows youngstock some level of exposure to the parasite so that they gain longer-term immunity, but also removes it before it is able to impact on productivity and further contaminate the environment.

Oral drenches such as Vecoxan are generally the most convenient way of ensuring that each calf or lamb receives the correct dose at the right time.

It is important to recognise that coccidiosis is only one of a number of causes of diarrhoea in calves and lambs. Farmers unsure about a particular disease management situation, should contact their vet for advice.

Dr Kat Baxter-Smith is veterinary adviser for MSD Animal Health