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Cobalt deficiency
Cobalt is not used directly by the sheep: it is the micro-organisms in the rumen which use it to produce vitamin B12, essential for energy production and blood formation. When the soil and grass lack it, the production of vitamin B12 stops...
What is it?
Cobalt is not used directly by the sheep: it is the micro-organisms in the rumen which use it to produce vitamin B12, essential for energy production and blood formation.
When the soil and grass lack it, the production of vitamin B12 stops and the animal is no longer able to value what it eats. He grazes normally and is still losing weight.
Breeders in several countries call this disease wasting, or pine: the lambs stagnate, decline, become thin and without energy even though the pasture seems good.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
The first sign is a loss of growth in lambs, usually a few months after weaning, when grass is available and of good quality.
The animals initially eat normally, then gradually lose interest in grazing; the flock spends less time grazing.
Slow weight loss, animals which become bony, dull, brittle wool which becomes loose and loses all value.
Paleness of the inside of the eyelid and gums, reflecting anemia which is slowly setting in.
Tearing and crusting around the eyes in some affected animals.
Fatigue from exercise, animals which stay behind the herd, which often lie down.
In advanced forms: very thin, listless animals, which eventually die without any other disease being found.
Adult ewes last longer, but they produce less milk, raise their lambs poorly and have difficulty rebuilding after lactation.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The cause is the lack of cobalt in the soil, and therefore in the grass and fodder produced on the farm. Certain soils, notably sandy, acidic or very calcareous, naturally provide little.
Heavy liming or high soil pH makes cobalt even less available to the plant.
Rations based on cereals and poor fodder, without mineral supplements suitable for sheep, do not compensate for anything.
Rapidly growing young and lactating females have higher needs: they are the ones who express the deficiency first.
Finally, parasitic damage to the digestive tract or acidosis disrupts the rumen flora and further reduces the production of vitamin B12, which worsens the situation.
Regions and plots whose soils are known to be poor in cobalt: the neighborhood generally encounters the same problem.
Lambs after weaning and young growing ones, which are the most sensitive.
Ewe at the end of gestation and lactating.
Diet based solely on grass and forage from the farm, without mineral supplements.
Generic mineral supplement not intended for sheep, or licking stone that animals do not consume regularly.
Associated digestive parasitism, which masks and aggravates the deficiency.
Years of drought, where animals graze on poor and undiversified vegetation.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The diagnosis is delicate because the signs look exactly like those of digestive parasitism, undernutrition or other deficiencies: a veterinary examination is essential before concluding.
The veterinarian begins by examining the entire flock, weighs the lambs and compares their growth to what is expected, examines the color of the mucous membranes and the condition of the wool.
He has a dropping analysis carried out to rule out or quantify parasitism, which is the primary cause of wasting in grazing sheep.
Blood tests allow vitamin B12 to be measured in several animals in the group, which gives an image of the group. Liver analysis on a dead or slaughtered animal is another way to confirm.
Analyzing the farm's forage and soil helps to understand the origin of the problem and decide on a lasting correction.
A practical point widely used in the field: the veterinarian can suggest a supplementation test on a batch, keeping a control batch, and compare the growth. A clear response strongly guides the diagnosis.
Treatment
The correction involves the provision of cobalt or directly vitamin B12, on prescription and in a form chosen by the veterinarian.
Several routes exist: injection by injection for a rapid effect on already affected animals, regular oral intake, specific ovine mineral blocks and supplements, or slow release devices placed in the rumen. The choice depends on the management of the herd, the number of animals and the possibility of handling them.
No dose, no rhythm and no concentration should be decided alone: excess mineral supplementation can unbalance other elements and cost a lot of money for nothing.
Treated animals regain their appetite fairly quickly, but weight gain and wool repair take several weeks.
Correction of parasitism and a ration correctly balanced in energy and protein must accompany the treatment: on their own, neither cobalt nor dewormer will rehabilitate an undernourished herd.
Be careful with products sold without a prescription and mixtures intended for other species: in sheep, certain supplements intended for cattle provide toxic amounts of copper.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Have the fodder and, if necessary, the soil analyzed to find out if the farm is really concerned: we do not add to chance.
Make a mineral and trace element supplement formulated for sheep permanently available, in a form actually consumed by the animals, and check that the tank is empty.
Strengthen coverage of needs during sensitive periods: lambs after weaning, ewes at the end of gestation and lactation.
Consider with the veterinarian a slow release device for herds on the move, which are difficult to supplement regularly.
Control digestive parasitism, which systematically worsens the picture.
Monitor the growth of the lambs by regular weighing: a dropout detected early avoids months of loss.
Never use mineral supplements intended for cattle or poultry in sheep, because of copper.
Possible complications
Growth retardation which never completely recovers in affected lambs while they are growing.
Anemia and general debilitation, with increased susceptibility to parasitism and infections.
Devalued wool, thin carcasses, downgraded lambs for sale.
Ewes in poor condition at birth, lambs small and weak, milk production insufficient to raise the litter.
Mortality of the most affected animals if nothing is corrected.
On a farm, an unidentified deficiency can cost several seasons of poor results wrongly attributed to parasitism.
When to see a veterinarian
Your lambs are no longer gaining weight even though the grass and feed are correct.
Several animals from the same batch slowly lose weight, with dull wool shedding.
The mucous membranes of many animals are pale.
The herd spends less time grazing and appears to have no energy.
The results do not improve after properly conducted antiparasitic treatment: you have to look elsewhere.
Neighbors report the same problem in the area: this points to a lack of soil.
Prognosis
Corrected in time, the deficiency responds very well: the animals regain their appetite in a few days and their general condition in a few weeks.
Severely affected lambs in full growth often remain permanently delayed: this is the true cost of the disease.
On a farm scale, the prognosis is excellent once supplementation becomes routine, because the cause is perfectly controllable.
Frequently asked questions
My lambs are no longer gaining weight despite deworming, is it necessarily worms?
No, and that’s precisely the trap. Parasitism remains the primary cause, but if the droppings are clean and growth remains poor, a cobalt deficiency is one of the explanations to examine with the veterinarian. A blood test on a few animals in the batch allows us to decide.
Is a salt lick enough?
Only if it is intended for sheep and if the animals actually consume it, which is far from always being the case. Many blocks remain intact for months. Check that it can be consumed and discuss the form best suited to your behavior with the veterinarian.
Can I give my sheep the mineral supplement from my cows?
No. Supplements intended for cattle contain much more copper, which sheep store in their liver and tolerate very poorly. It is a known cause of fatal poisoning in sheep farms. Only use products bearing the sheep label.
Is this deficiency linked to my region?
To a large extent, yes: it depends on the cobalt richness of the soil. If neighboring farms encounter the same growth problems, the hypothesis of a sector deficiency becomes serious and an analysis of the fodder is useful.
References
FAO — Organisation des Nations unies pour l'alimentation et l'agriculture
ANSES — Agence nationale de sécurité sanitaire (France)
Content reviewed by the TunisieVet editorial team · Updated 11 August 2026
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