Iceberg disease is a term used in human medicine described as "a disease in which, for every visibly affected individual, the population will contain numerous others that are sub-clinically infected, carriers or undiagnosed clinical cases". The term covers 5 conditions (discussed below) with each affecting sheep productivity and performance at various stages of the sheep's life. A recent study suggested that only 5% of UK flocks routinely test for iceberg diseases and therefore a staggering 95% of flocks are not optimising productivity!
Effects on KPIs
All iceberg diseases will negatively affect key performance indicators (KPIs) in flocks. A decrease in reproduction rates is common, in the worst cases up to 50% reduction in lamb output has been reported during one lambing season! Maedi Visna will decrease fertility rates by roughly 9% when compared to unaffected flocks; whereas Border disease can range from 2-8%.
Lamb survival, ewe and ram lifespan are also impacted. Growth rates in lambs infected with Border disease can be reduced by 20% (roughly resulting in a 2.5kg weight difference by 6 weeks of age!).
A report in 2019 on the effects of Maedi Visna showed that lambs from infected sheep (showing no signs) weighed nearly 1kg less at weaning, resulting in a loss of £4.07/lamb assuming 20% of the flock is affected (this value will be much higher now considering the current lamb price!). This does not take into consideration cull ewe costs and replacement costs which would result in further financial losses!
Our latest SHEEP NEWSLETTER covers Border Disease, Maedi Visna, CLA, Ovine Johnes and OPA, looks at the impacts and the opportunities for testing. Please do call us for any further information on 01666 823035.