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Extended Winter Putting Ewes At Extra Risk - SAC Offers Discounted Rates For Blood Testing

SAC News Release Ref. No: 10N17
Published: 04 Mar 2010

Blood test could help ewes at risk (opens in new window)

There is increased concern that the recent return to severe winter weather is putting pregnant hill and upland sheep under extra pressure.

With fears that some sheep may be at risk of approaching lambing in an undernourished state SAC Consulting: Veterinary Services are offering specially discounted rates for special blood tests that would help sheep farmers spot any problems early and allow them to take immediate action.

Freezing temperatures and drifting snow can disrupt normal feeding patterns and create extra stress for animals already under pressure, especially if they are carrying twins or triplets.  If they cannot reach food, or feeding is interrupted, pregnant ewes are forced to fill the energy gap by using their own fat reserves. This increases the risk of them developing twin lamb disease or “pregnancy toxaemia”, from which less than a third of those affected will recover. Spotting problems early is essential.

According to Perth based SAC Vet Graham Baird, “The best way of spotting a potential energy gap is to blood test a selective sample of the flock. The test, which measures a chemical called BOHB, tells us if the ewes are underfed. Another test for urea identifies whether ewes are getting enough protein in their diet, another vital factor for developing lambs.” 

Normally these tests are best done around a month before lambing, it will give shepherds time to make any necessary changes to their flocks diet. For those flocks which have been pregnancy scanned  shepherds can sample five ewes carrying twins and five with triplets. Make sure they are early-lambing sheep in average body condition. In flocks which have not been scanned sample ewes in average condition.

Until 15th April, 2010 SAC Veterinary Services is offering tests for BHOB and Urea in up to ten animals for a flat rate of £25.00 +VAT. Shepherds should discuss with their vets whether this sort of testing is something they should be considering.

For further information please contact Graham Baird, SAC Consulting: Veterinary Services.

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News Release Contacts

SAC Contact

Mr Graham Baird
Veterinary Centre Manager
SAC (Scottish Agricultural College) Work Perth Veterinary Centre, 5 Bertha Park View,
Perth
PH1 3FZ
TelWork 01738 629167
Fax 01738 643198

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News Release Issued By

Mr Ken Rundle
Senior Communications Officer
SAC (Scottish Agricultural College) Work SAC, King's Buildings, West Mains Road,
Edinburgh
EH9 3JG
TelWork 0131 535 4196

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Further Information

News Release Reference Number: 10N17


  • In late pregnancy ewes have a high demand for protein and energy (and in particular glucose) as the foetus develops and they prepare to produce milk. To meet these high energy requirements, the animal can either increase the amount of energy taken in from the diet or mobilise body reserves of fat and protein.  Any shortage of feed puts additional pressure on those body reserves. 
  • This problem is particularly acute for the ewe since more than two thirds of foetal growth occurs during the last third pregnancy. An additional factor is the size and weight of the uterus of a pregnant ewe, which is proportionately far larger than in other farm species.  This takes up extra space in the abdomen, restricting the bulk of food the ewe can take in to less than two per cent of bodyweight, far less than is required to fulfil typical energy demands.  This places ewes that are on a low energy diet and in poor condition to start with at particular risk of pregnancy toxaemia, especially if they are carrying more than one lamb.
  • One outcome of excessive mobilisation of body reserves is the production in the liver of ketone bodies such as b-hydroxybutyrate (BOHB).  For groups of scanned sheep a target mean BOHB should be 1.0 mmol/l; with the corresponding figure being 0.8 mmol/l in flocks where scanning is not performed and litter size is therefore unknown.
  • Measurement of blood BOHB levels in sheep gives a more immediate assessment of energy balance.  As this is a flock-based measure, at least five animals need to be sampled from each management group and it is important to avoid any animal with obvious disease problems that might skew the results. 
  • The mean serum urea result should be >2mmol/l.  Peas, beans and soya are protein sources that could be introduced if results are low.  Distillers’ dark grains and urea could be used but the potential risks of copper and urea toxicity should be borne in mind. The ewes should then be re-sampled two weeks later to check that the deficit has been corrected. 

SAC Consulting Veterinary Services is part-funded by the Scottish Government as part of its Public Good Veterinary and Advisory Services.

Notes for Editors