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Pre-Tupping Nutrition – A Targeted Approach Is Best For Ewes

Nutrition in the run up to tupping is critical to ensure success. Every year farmers are spending money on various supplements for their ewes often without knowing what they actually require. To guarantee optimum nutrition you should be working with your vet to determine the current trace element status of your flock and your vet can then advise which trace elements, if any, are required. Nutrition in the run up to tupping is critical to ensure success. Every year farmers are spending money on various supplements for their ewes often without knowing what they actually require. To guarantee optimum nutrition you should be working with your vet to determine the current trace element status of your flock and your vet can then advise which trace elements, if any, are required.


Copper plays a vital role in the health and fertility of sheep. It is needed for the production of the enzymes that are required for fertility and thrive, as well as for healthy wool and white blood cell function. White blood cell function is vital to the immune system which defends the sheep against disease and parasites.

Furthermore, during gestation the ewe requires copper to develop the lamb’s nervous system. Without an adequate source of copper mid-pregnancy the lamb’s nervous system is not formed correctly and cannot be treated - this is known as swayback.

Copper should never be supplemented without first consulting a vet to establish that there is a need, as excess copper can result in copper toxicity which can prove fatal. Housed sheep, sheep which are due to be housed within the next 6 months and continental breeds and are particularly susceptible to copper toxicity.

The below table highlights how susceptible some of the UK’s most common breeds are to copper toxicity:

Highest Risk Breeds High Risk Medium Risk
North Ronaldsay Zwartbles All other breeds
Blue Faced Leciester Charollais Cheviot
Texel Suffolk/Lleyn Scottish Blackface

While copper deficiency can be caused by insufficient copper in the sheep’s diet, this is actually relatively rare. It is far more likely that sheep are ingesting adequate levels of copper, but that they are also ingesting high levels of other elements which either antagonise copper or cause harm after absorption. This includes:

  • Molybdenum
  • Sulphur
  • Iron

Cobalt is required by the rumen microbes for the production of Vitamin B12 which is important for thrive and fertility. Cobalt is also critical for growth in lambs.

The body has no capacity to store cobalt, therefore it must be continuously supplied. This means that a cobalt drench is not suitable to address an established cobalt deficiency. While drenches can be cheap and convenient, they are also a false economy to treat established cobalt deficiency. The excess cobalt cannot be stored and simply passes out of the animal in faeces.

Instead, a slow-release, continuous supply form of supplementation should be used, such as a bolus.


Selenium is vital for muscle function and deficiency can result in white muscle disease. Selenium deficiency is also a cause of impaired fertility, impaired growth, poor wool quality and reduced immunity.


Like cobalt, iodine is a trace element that ruminants have no capacity to store and a continuous supply must therefore be available. Where the animal’s diet is unable to provide this, supplementation will be required.
Where a deficiency has been identified and requires supplementation I would always advocate in favour of supplementation which supplies trace elements at a controlled and constant rate over long periods - making boluses particularly suitable.

Sheep deficient in iodine may suffer from:

  • Poor growth and weight loss
  • Reduced hormone secretion and reproductive health
  • Reduced bone growth and skeletal development

Furthermore, ewes will not be able to transfer sufficient amounts of the element to the unborn lamb. This can result in lambs being born weak or dead.

What Action Should I Take For My Flock?

Trace element status will vary from farm to farm and even from field to field!
There is no way to know which deficiencies or toxicities exist unless you carry out the diagnostics.
The best way to determine this is by blood sampling a number of the ewes and taking samples of the forage which they are consuming. Your vet can advise how many samples are required.

When Should I Take Action?

If trace elements imbalances are present in your flock you need to implement any dietary changes at least 4 weeks prior to tupping to ensure the full benefit of correcting the diet.
As such, blood sampling ewes and collection of forage samples should be carried out 6-8 weeks before tupping. This allows plenty of time to get the results back and implement any changes.

Which Product Is Right For My Flock?

If your vet diagnoses a trace element deficiency and has advised you to supplement trace elements you have a number of options including:

Oral Drenches

Drenches can seem like a cheap and convenient option. However, for trace elements which cannot be stored in the body, such as cobalt or iodine, they are not appropriate to treat deficiencies- a continuous form of supplementation must be supplied.

If you provide cobalt via a drench, the excess that the body cannot use will simply be passed out in the faeces. This means that they are in fact a false economy for the farmer. Frequent dosing is required, which increases costs to the farmer, both in terms of the drench itself and labour required.

Free Access Systems, Such as Licks and Blocks

We need to ensure that all animals receive an amount of trace elements which is compatible with their daily requirements. Too much of a trace element can prove toxic; too little and the deficiency will not be addressed.

Unfortunately, the free access lick and block systems do not provide this guarantee and an independent study highlighted that intakes between animals are extremely variable, with some consuming nothing and others consuming excessive quantities.1 In another study, 50% of ewes were shown not to consume any supplement at all.2 A more scientific approach to supplementation is required.


Injections can be suitable for targeted administration in conjunction with the advice of your vet. They can be appropriate where only a single trace element, such as copper, is required.

Pasture Dressing and Water Supplementation

Like blocks and licks, these forms of supplementation suffer from variable intakes. It is also difficult in practice for hill sheep, due to the extensive nature of hill sheep production.

In Feed Supplementation

Trace elements can be provided by the provision of TMR, concentrates or bag minerals.  Often these are specified based on ‘averages’ or ‘common requirements’ as opposed to being based on what has been determined is deficient and required on farm. Ideally these mixes should be prepared based on an investigation to address the animals’ specific trace element requirements.

This method can add significantly to the cost of production and can be difficult for hill sheep due to extensive conditions.

Trace Element Boluses

Boluses provide an convenient and controlled method of trace element supplementation. This means there are no variable intakes and no guesswork for the farmer. This is particularly important for animals requiring cobalt and iodine which cannot be stored in the body and therefore a daily supply is required. Their long-lasting nature is also highly convenient and reduces labour costs as regular bolusing is not required.

Only the Cosecure and Coseicure boluses supply rumen-available ionic copper and cobalt.  The most important thing to remember is to ensure that a need for trace element supplementation has been established before supplying any form.

Date editorial Prepared: July 2017
CoseIcure sheep bolus contains copper, cobalt and selenium and iodine.
Only provide trace element supplementation where a need to do so has been established by a vet or nutritionist. Some breeds of sheep and more susceptible to copper toxicity including blue faced Leicesters, north ronaldseys and texels.


  1. McDowell, 1992
  2. Kendall, 1997

About the author:
Rachel Mallet is a Veterinary Surgeon, who now works as a Professional Services Vet providing technical support to vets, SQPs and farmers in the UK. Rachel is passionate about animal health and about promoting best practice and preventative medicine amongst farmers.