Coccidiosis – The True Effect on Lambs
2012-04-16

The prevalence of this economically challenging condition is often more noticeable at this time of year as lambs are most commonly clinically affected between the ages of 4-7 weeks, warns James Brinicombe, R&D Director of the Denis Brinicombe Group. This disease affects lambs indoors and at grass with equal measure, although intensively reared lambs may be at greater risk.

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Ewes are usually asymptomatic carriers; they have an immunity and resistance to the parasite and therefore show no sign of disease. Ewes will excrete oocysts at parturition when their own immunity is compromised thus leaving lambs open to picking up an infection from birth. A lamb’s first exposure to the disease will always come from the ewe, with constant re-infection from the environment. The environmental level becomes a bigger problem as the lambs mature and the burden increases. Flocks with an extended lambing period are likely to have a higher incidence in the later lambers due to the ever increasing environmental burden that lambs are exposed to.

At a sub-clinical (also known as ‘Economic Coccidiosis’) level, affected lambs may show no symptoms whatsoever, however these will be the lambs that you are struggling to finish in the back end. A sub-clinical infection in the flock is most likely to manifest itself as poor growth in young lambs, due to the poor nutrient absorption from the food passing through the intestine, there may also be a few with dirty backsides that do not clear after worming. The immune status of the lambs will be compromised which will also leave them susceptible to other disease and infections, warns Mr Brinicombe.

Lambs suffering from clinical Coccidiosis may exhibit a variety of symptoms, most usually scour, often dark and blood stained, dullness and rough appearance, loss of appetite, weakness and dehydration. Death can follow if left untreated.

Coccidiosis is a progressive disease of the intestines; the coccidia attack the intestinal lining, invading the cells and multiplying before being excreted in the faeces. One oocyst ingested can be responsible for one million oocysts excreted.

It is worth considering that clinical Coccidiosis could be a symptom of a greater problem; poor immunity, stress in the flock, poor hygiene, stress or disease can all lead to an outbreak of Coccidiosis. Hygiene is very important in the control of Coccidiosis, but cannot control it alone; unfortunately it is resistant to the usual disinfectants, states Mr Brinicombe.

Coccidiosis in either sub-clinical or clinical form can significantly impair lamb growth and performance, so steps should be taken to either prevent or control an outbreak to reduce the associated economic losses, concludes James Brinicombe.

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