MAFFchecks out vitamin E
By Marianne Curtis
CONTROVERSY about levels of vitamin E required in late-pregnancy ewe diets to enhance lamb vigour and growth has led MAFF to promise new research, designed to improve advice to producers.
Research at ADAS Redesdale, Northumberland, last year, indicated that lambs from ewes supplemented with 100iu or 100mg of vitamin E a day for the last 70 days of pregnancy were quicker to suck and gained 1kg more to weaning than lambs from ewes fed a non-supplemented diet.
However, putting a figure on vitamin E recommendations is not straightforward. Many factors need to be taken into consideration. A recent MAFF chief scientists group sponsored seminar summarised current knowledge and proposed further research.
Vitamin E deficiency – most commonly recognised as muscular dystrophy in lambs – is not a new problem. But greater awareness and higher performance expectations from modern sheep mean it is recognised more often, the seminar group found. MAFF research hopes to identify risk categories for different situations, says the head of its of livestock and biotechnology unit, David Garwes. "Increasing vitamin E levels for all sheep is expensive if they dont all need it.
"We aim to identify risk levels and get a feel for the scale of the problem. The research team will seek producer experience information and look at the effects of factors such as breeds, systems and seasons on vitamin E requirements," says Dr Garwes.
Factors likely to increase vitamin E requirements were identified at the seminar. Modern, faster growing breeds have lower fat deposits available for vitamin E storage, which might make them more susceptible to deficiency. Coccidiostats and diet also have an effect.
For these reasons, independent sheep consultant, Lesley Stubbings says that it is not easy to say what the ideal vitamin E level should be. The Shire Lamb buying group, which she advises, purchased ewe feed supplying an additional 45-50iu/day of vitamin E last season.
"We had no problems associated with vitamin E in the group but may request 70iu a day this season to increase the safety margin." Feed processing can destroy vitamin E and level of destruction varies between mills, she explains.
Diet changes and using in-feed coccidiostats can also increase vitamin E requirements, explains Ms Stubbings. "Straw is a poor source of vitamin E; it only contains 3-10mg/kg. Grass silage and hay are better sources but contain variable amounts. Fish oil – from fishmeal – is a very good source but ewe rations often contain no fishmeal.
"Coccidiostats destroy vitamin E. Ewes must not be fed coccidiostats; they are a waste of money and may do more harm than good," she adds.
As blood sampling is of limited help in assessing a flocks vitamin E status, Ms Stubbings recommends that producers work out whether they are in a high or low risk situation. "Ewes grazing a green crop – not roots – will be less at risk from vitamin E deficiency than ewes fed straw. If you think your flock is in a high risk category, talk to a nutritional adviser or vet." *
• Flock requirements vary.
• Many factors involved.
• Research to identify risks.