Vital trace elements in the blood of growing lambs can hit performance-limiting levels just weeks after weaning, warn experts.
Trials by feed specialist Agrimin and Trefaldwyn Vet Practice, Powys, found all lambs had adequate amounts of trace elements at weaning, but by six weeks they dropped below the recommended level, says Agrimin’s Ieuan Davies.
“Looking at selenium levels alone, 90% of the lambs without any supplementation were well below the recommended 50U/ml red blood cells just 40 days later.
“This is a critical period for lamb growth and trace elements have an important role in ensuring the best start in life.
“Problems arise following the nutritional stress of weaning,” he says. Selenium, for example, is a strong antioxidant that promotes growth by improving the function of muscles and vital organs such as the liver.
Cobalt is essential for producing the vitamin B12 required by rumen micro-organisms to drive feed conversion efficiency and development.
The growing practice, encouraged by environmental schemes, of overwintering ewes on roots and brassica crops is causing a particular problem, Mr Davies says.
“Iodine, produced by the thyroid gland, is essential for healthy, consistent growth rates.
“But rape, roots and other brassicas inhibit the absorption of iodine in ewes, which then affects the developing lamb.”
Vet Q&A with Helen Latimer, Tethera Vets, Cumbria
Why can trace element deficiencies in lambs occur at weaning?
At weaning, lambs are on their own nutritionally, which can be a shock to the system. Trace element shortages are most likely when animals are under stress and this is very much the case with lambs post-weaning.
There are also interactions with some common feedstuffs. For example, brassicas limit the availability of iodine and molybdenum in feed or forage can tie up copper.
After lambs are weaned, their own nutrition should be carefully assessed to ensure they are getting enough nutrients for themselves.
Can the weather affect mineral levels?
We have seen several incidences recently where producers have experienced new trace element shortages for the first time.
The variable weather of recent years has contributed to some key minerals being leached out of soils.
The remaining imbalance further complicates matters by affecting absorption of key nutrients.
What specific trace element problems are associated with lamb health and vitality?
Cobalt and selenium, in particular, are essential for good lamb growth. Deficiency in cobalt (vitamin B12) can manifest itself in signs of pine – poor growth, dull fleece and lack of overall vitality.
It can also cause anaemia, which can affect the immune system.
Selenium deficiency in growing lambs can present as white muscle disease, a wasting condition with a devastating effect on the lamb.
Which are the most common trace element problems you see?
Pine is very common and even slightly low levels of cobalt can cause poor growth rates, but they often only appear as a subclinical problem. In many cases issues are only picked up if producers keep good records of weight gains.
What is the conventional way of treating trace element deficiencies in lambs?
It depends on which trace element is deficient. If it is solely cobalt (vitamin B12) then injection or oral drench can be considered, but these do not last long.
It would be good to bolus, and until now no effective option has been available.
However, the new Agrimin bolus that keeps blood levels of all key trace elements at the right levels for 120 days is a real breakthrough.
If it is just selenium that is lacking, then again there are injections or drenches available. But a long-lasting, slow-release bolus would be an all-round solution.
Is regular blood testing something you would recommend?
Yes. It is the only way you can get a real picture of what is going on. Test about eight to 10 animals per 100 every one to two years and respond to the problem accordingly.