Monitoring Trace Element Status
18 October 2017There are three main reasons to check trace element status:
- To investigate poor production or symptoms that could be related to a deficiency.
- Routine monitoring to investigate whether levels are adequate and decide whether supplementation is required.
- To check whether supplementation is working.
You need to decide which animals to sample and when to sample.
Copper
Possible problems in sheep
Swayback
Ill thrift (less common in sheep than cattle)
Skeletal abnormalities (fractures)
Possible problems in cattle
Ill thrift
Coat changes
Diarrhoea
Reduced fertility
Anaemia
Skeletal abnormalities
Poor milk yield
Possible times to blood sample for routine monitoring*
Ewes – pre tupping;
scanning or pre-lambing
Lambs – around weaning
Cows – pre-bulling
Calves – around weaning/housing
Cobalt
Possible problems in sheep
Ill thrift
Ocular discharge
Anaemia
Poor wool growth
Reduced immune function
Poor fertility
Neonatal losses – reduced milk yield, poor mothering, reduced lamb activity
Photosensitisation
Possible problems in cattle
Ill thrift (less common in cattle than sheep)
Ocular discharge
Reduced immune function
Poor milk yield
Possible times to blood sample for routine monitoring
Ewes and lambs – as for copper
Cattle – the blood test is not particularly useful in cattle
Selenium
Possible problems in sheep
Ill thrift
Poor fertility (tups)
Increased barren rate due to embryo loss
Stillbirths, weak lambs
White muscle disease
Reduced immune response
Possible problems in cattle
Ill thrift
Reduced fertility
Stillbirths
White muscle disease
Reduced immune response
Possible times to blood sample for routine monitoring
Tups and ewes – pre tupping (at least 8 weeks earlier for tups.)
Ewes – scanning or pre lambing
Lambs – around weaning
Cows – mid to late pregnancy
Calves – around weaning/housing
Iodine
Possible problems in sheep
Poor scanning results
Increased perinatal lamb deaths
Goitre
Possible problems in cattle
Increased perinatal calf deaths
Goitre
Possible times to blood sample for routine monitoring
Ewes – pre tupping/lambing
Cows – mid to late pregnancy
* Discuss with your vet as the best timing will depend on management and previous history.
If sampling, e.g. pre-calving, always allow enough time for supplementation to be given if it should be required. Remember that many of the problems listed have many possible causes and trace element deficiency is not always the explanation.
Heather Stevenson, healther.stevenson@sac.co.uk
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