News Article

Trace Elements in Sheep - Part 3

Friday, 1 December 2017 - 4:50pm

Selenium, Iodine & Cobalt


Although the classic presentation of deficiency is white muscle disease, with lambs becoming stiff legged, it can also be a cause of weak lambs, high lamb mortality, and poor fertility in ewes.  Blood samples can give a good indication of selenium status over the past 2 months.  The diagram below shows the role of selenium and vitamin E in binding free radicals.


Iodine is important for immunity of ewes and lambs, so deficiency can increase levels of watery mouth and joint ill in lambs.  It can also be a cause of stillbirth, which can be diagnosed by weighing the thyroid glands of stillborn lambs.  Adequate levels of iodine are also important for ewe fertility.

Testing for iodine is carried out by pooling blood samples from up to 6 sheep, as individual testing is expensive.


Cobalt is required to produce vitamin B12, which is an essential part of the energy metabolism pathways, so it is important for both lamb growth and ewe fertility.  Blood samples can be taken to measure B12 which gives a good measure of cobalt levels.


Blood samples can be taken from at least 6 typical ewes, or lambs, to establish the current levels of copper, selenium, cobalt and iodine.  If you are already providing some supplement it is still worth testing as the levels achieved by different licks, boluses and drenches are very variable.

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