SHEEP farmers preparing for the 2027 lambing season are being urged to keep a close eye on cobalt levels, with deficiencies potentially affecting the health and vigour of newborn lambs.
Cobalt is one of a number of essential minerals and trace elements which can have an impact on flock performance, but deficiencies can be difficult to spot before problems emerge.
Dr Alison Bond, Technical Services Manager at Rumenco, says the variable nature of cobalt levels in grassland soils means its availability can be particularly difficult for farmers to monitor.
Heavy rainfall and flooding, changes in soil pH, organic matter content and cropping can all influence cobalt availability.
Dr Bond recommends routine soil and forage testing to establish levels of cobalt and other essential minerals, alongside appropriate supplementation where deficiencies are identified or suspected.
She said: “Whilst the situation with many of the important minerals is relatively easy to ascertain, cobalt is more difficult because levels can vary quite significantly on any given site.
“This may be due to changes in soil pH, perhaps due to liming, for example, shifts in the soil organic matter content, or excessive cropping. Factors such as heavy rainfall, or severe flooding, can also cause a change in the soil cobalt status.”
Cobalt plays an important role in the production of vitamin B12 by microorganisms in the rumen. Where vitamin B12 is deficient, sheep can experience poor growth rates, weight loss and anaemia.
Of particular concern to sheep producers is the potential effect on lambs born to ewes experiencing a sub-clinical deficiency – where cobalt levels are inadequate but there are few or no obvious outward symptoms.
Dr Bond highlighted independent research carried out by SAC which examined lamb activity during the first three days of life, including exploration and how frequently lambs nosed their mothers.
These behaviours are considered important indicators of colostrum intake and the longer-term viability of newborn lambs.
She said: “This work shows very clearly that lambs born from ewes with sub-clinical cobalt deficiency, which is typically without symptoms and goes unnoticed, had lower levels of activity, less exploration, and fewer instances of nosing.
“The ewes in the control group, with adequate cobalt status, produced lambs that were far more active, seeking the teat more regularly and with greater success.”
She added that the difference could ultimately contribute to whether farmers experience a relatively straightforward lambing period or have lambs which require greater intervention and are less likely to thrive.
With the tupping period approaching for many flocks, farmers are being advised to consider the mineral status of ewes ahead of mating and provide appropriate supplementation where necessary.
Mineral buckets and feed blocks can provide one option where grazing or conserved forage is unable to meet the flock’s nutritional requirements, although the appropriate approach will depend on the needs of individual farms and flocks.
Recent extremes in weather have made regular monitoring increasingly important, according to Dr Bond.
She said: “In the last two years alone, we have seen excessive rainfall and extensive flooding, which has increased the amount of nutrient leaching from soils.
“We know from the results of forage sampling on a national scale that this is having an impact on mineral and trace element availability, and not just for important minerals like cobalt.”
She said more regular forage analysis could help farmers identify gaps in nutrient availability before they begin to affect livestock performance.
“With the unprecedented weather events that we’re increasingly seeing, it is far safer to increase testing than to assume grazing and forage quality remains the same,” she added.
