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Cobalt always worth remembering

By Joanne Marshall-Crack

Some things never change – and one of those things/or issues is cobalt deficiency.

It seems like every five years I write about cobalt deficiency and what to look out for etc – that information is still essential and many people will have already done something this season to combat cobalt deficiency – if it’s a problem in the area

Farmers might recall that in late March and early April the cobalt didn’t seem to be working as well.

Several years ago we wrote about contacting Rex Dolby, of Agro Science Consultancy Services in Dunedin, who said that there were very good reasons for this occuring.

He said that spraying cobalt on pastures works best when the pastures were growing rapidly. “If you are only spraying it on immediately ahead of the animals then all you are doing is drenching them. It should be sprayed on some time ahead.”

He also pointed out that if the pasture has gone to seed (and even if cobalt has been applied in the past) then cobalt deficiency will be a certainty.

Another point he raised was that farmers often make the mistake of waiting and “leaving the stock until they are deficient.”

When this happens the animal loses its appetite and is far less likely to eat enough cobalt-treated pasture to lessen its deficiency.

This is when, and why, Vitamin B12 will work better than spraying cobalt on (at certain times of the year).

Dr Dolby also said that to treat, and prevent, cobalt deficiency it was important for farmers to know the soil types they are working with.

“The ability of the cobalt to last in the soil will depend on the soil type.”

And, it is important to realise that if the property is fairly deficient then Vitamin B12 injections (not the long term one) will last for only about four to six weeks.

In the case of applications of cobalt to pasture then 40g per hectare will last about six weeks whereas 120g/ha would last 10 to 12 weeks.

Drenching?
This is an option although a cobalt drench will last only one to two weeks.If you were to drench the animals it would actually be the second drench that would show some affect. The first drench would merely be used to satisfy the cobalt needs of the bacteria in the animal�s gut.

Other factors which can have an affect on the animals’ cobalt status include:

* The level of clover in the pasture (clover has double the level of cobalt than grasses).

* Cocksfoot and Timothy are lower in cobalt than ryegrasses.

* Ingestion of soil. While this is detrimental in the case of copper deficiency it works favourably in the case of cobalt deficiency.

Interesting points

* Deficient animals cannot store cobalt.

* As an animal becomes more cobalt deficient it is more susceptible to other diseases and problems such as heavy worm burdens. But Dr Dolby said that an animal with a heavy worm burden was also more likely to suffer from cobalt deficiency.

Many farmers treat the symptoms of cobalt deficiency rather than altering their management practices, he said.

“They are only plastering the cracks. They have to deal with the cause rather than the affect.”

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