17 April 1997

Vitamin E during pregnancy may mean more viable lambs

By Emma Penny

HILL and upland sheep producers might in future be able to increase lamb viability using a long-acting vitamin E bolus inserted at scanning.

Recent research has shown that dosing ewes with vitamin E in the last eight weeks of pregnancy increases levels in blood and colostrum, promoting lamb vigour, explains Brian Merrell, based at ADAS Redesdale, Northumberland.

"Where ewes are fed concentrate it is easy enough to increase vitamin E levels in feed to boost lamb viability. But it is more difficult in hill and upland flocks, where ewes may not receive any concentrate."

For vitamin E supplementation to be useful in hill and upland flocks – where better lamb vigour is most needed – ADAS researchers looked at all dosing alternatives. "Most of all, it had to be practical, requiring no additional gathers, and fit in well with systems," he says.

Feed blocks were rejected because intake is too variable. Injecting vitamin E, including it in a pre-lambing wormer dose or in a clostridial vaccine were deemed useless because of poor longevity. "Where injections were used, ewes would have to be treated three times every two weeks, which is poor for both welfare and management reasons."

But a slow release bolus – the only option left – could hold the key, believes Mr Merrell. "We needed a bolus which could be implanted at scanning and would give an eight week release of vitamin E. But vitamin E is low density, which means a huge bolus would be needed."

That concern has been solved by using patented new technology. Now a prototype smaller bolus has been produced using vitamin E oil.

"This has one small problem – it is not stable at room temperature and has to be kept refrigerated before use. But we are trying to prove the principle, and are using it at ADAS Redesdale and Pwllpeiran. If current trials are successful we will try to develop a better commercial product," explains Mr Merrell.

Trials are also looking at use of two joined boluses which can be inserted in a single action, but while one starts to release vitamin E immediately, the other is coated and remains inert until the first bolus runs out.

"Dose response rate is another area we are looking at in more detail. We know that feeding 150iu gives a response, but we do not know exactly how much is needed, so have set up a trial to look at what the optimum rate is. The boluses give about 100iu a day, but that might change given the results of this trial," he adds. &#42


&#8226 Boosts lamb viability.

&#8226 Use slow release bolus?

&#8226 Implant at scanning.

Slow release boluses, implanted at scanning, may be one way to boost the vitamin E in hill ewes, and improve lamb viability, say ADAS researchers.