The effects of molybdenum

Molybdenum is an essential element associated with a variety of metalloenzymes and corresponding metabolic functions. Excessive dietary intake of molybdenum induces a secondary copper deficiency. Cattle and sheep are 10-fold more susceptible to molybdenum poisoning than other species of livestock. Excessive liming of land will reduce herbage cobalt levels but increase molybdenum. Across the country as a whole molybdenum, iron and sulphur are important contributors to deficiency of copper. Soil is relatively rich in iron, sulphur and molybdenum and hence contamination of pasture or silage can reduce availability of copper to the animal. Compounds involving molybdenum, sulphur and iron form in the rumen and limit copper absorption

Why is copper needed?

Copper is one of many trace elements that is required by cattle and it is considered one of the most important.

Copper is required by the body in order to form numerous enzymes which are essential in order for the body to function to its full ability, with a lack of these enzymes resulting in signs of a deficiency of copper.

Signs of molybdenum problems

Typically, the syndrome is a herd problem, with morbidity as high as 80%. The clinical symptoms in cattle are characterised by severe, persistent diarrhoea with the presence of green, watery faeces containing gas bubbles. De-pigmentation, resulting in fading achromotrichia of the hair coat. This is often more noticeable in cattle with black hair e.g. Friesian’s, Holstein’s, Angus etc. A brown/reddish tinge can be seen on the coat.
Pica or lack of thrive, emaciation, joint pain characterised by lameness. Molybdenum competes with phosphorus utilisation also, resulting in reduced mineralisation of bone.
In heifers, fertility is reduced. Delayed puberty, poor conception rates, decreased weight at puberty, and decreased milk production are common. Reduced libido has been reported in bulls.
In sheep, particularly in lambs <30 days old, the animals exhibit stiffness of the back and legs and have difficulty rising. The syndrome in sheep is known as enzootic ataxia, or swayback. Abnormal development of connective tissue and growth plates are apparent in affected animals. Manifestations appear within 1–2 wk if molybdenum levels are excessive. It is more common that lambs are born with swayback than develop it over time. Pre-lambing nutrition is key in preventing the condition.
Breeds, such as the Texel, which absorb copper very efficiently, are at risk of copper toxicity. Whilst breeds such as the Scottish Blackface, which are less efficient at absorbing copper, are more likely to suffer from a copper deficiency

Dealing with Molybdenum to Optimise cattle/sheep performance

If molybdenum toxicity exists then increasing the intake of copper can prevent it by binding the molybdenum in the gut and thus preventing it getting into the body. However, copper is a poison, so if you are going to feed more copper you should only do so once you have calculated exactly how much copper you are feeding your cows. Too much copper will cause copper toxicity.
The type of copper used is important also. It is important that the copper used is in a safe and effective form that the animals can use.
Molybdenum and sulphur bind together to form something called Thiomolybdate. Thiomolybdate is very ‘copper-hungry’. It binds with copper in the rumen and when there is no copper left in the rumen, it moves into the bloodstream and binds to the copper-co-dependent enzymes there.
These enzymes are vital for fertility and productivity. When the molybdenum and sulphur combination (thiomolybdate) binds with these copper enzymes in the blood, they are rendered inactive, so fertility and productivity are impaired. Some farmers will know this as ‘copper lock’ or ‘secondary copper deficiency’

Options of supplementation

Iomlán Animal Science strive to work with our customers in solving and preventing problems on farm.

If it is already established that molybdenum and copper are already the causes of the lack of thrive, fertility etc. we can recommend a product and programme to suit your farm.There are several products available, all with the best forms of copper to deal with molybdenum and copper deficiencies.

“Blasta” bucket minerals
“Optimise” mineral drench range
Bolus range with our Iomlán capsules
Bag mineral range

The types of supplementation can suit all types of farming systems.