Monitoring Trace Element Status

There are three main reasons to check trace element status:

1. To investigate poor production or symptoms that could be related to a deficiency.
2. Routine monitoring to investigate whether levels are adequate and decide whether supplementation is required.
3. 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