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| Cobalt/vitamin
B12 deficiency - The
disease |
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Cobalt
is required by the rumen micro-organisms for the synthesis
of vitamin B12. A lack of cobalt
will therefore cause vitamin B12
deficiency in ruminants.
Deficiency causes loss of appetite resulting in poor growth.
The disease is therefore often referred to as a starvation
or wasting disease even though the animals are usually grazing
adequate feed.
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Effects on the animal |
Cobalt
deficiency in soil and/or pasture leads to a lack of vitamin
B12 in body tissues. vitamin B12
is essential in energy and protein metabolism.
Under deficient conditions, calves and lambs can thrive and
grow normally until they deplete their vitamin B12
reserves in liver and other tissue. They will soon lose appetite
and fail to grow. In severe cases anaemia, rapid weight loss
and finally death will occur.
Pastures that are marginally cobalt deficient result in low
vitamin B12 levels in the dam and can
cause birth of weak lambs and calves among which the death
rate can be high.
Even a marginal deficiency may cause poor production, particularly
poor growth rates in young stock as they are most sensitive
to vitamin B12 deficiency.
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| The
signs |
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In
severe cases, a watery discharge from the eyes may be seen
and anaemia, rapid weight loss and finally death may follow
this. In sheep, wool may appear white or washy with a reduced
growth rate. In cattle, dull harsh coats may be seen. Commonly,
impaired weight gain in lambs or calves will be the first
sign of deficiency noted.
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| Lost
production and reduced returns |
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Most
animals do not show any outward sign of the disease unless
there is a marked deficiency. The health and productivity
of affected animals can, however, be severely affected with
marked decreases in;
- growth
rates in young stock,
- fertility
and reproductive performance with more still births and
early deaths,
- milk
production, and
- fibre
production.
Vitamin
B12 deficiency affects profitability
through production targets not being achieved and reduced
returns.
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| Criteria
to assess vitamin B12 status |
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Cobalt
deficiency is best diagnosed by measuring serum and/or liver
vitamin B12 concentrations.
To
assist in determining the need for vitamin B12
supplementation the following criteria provide a guide.
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Serum
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Liver
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(pmol/l)
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(nmol/kg
fresh tissue)
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Low
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Marginal
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Adequate
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Low
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Marginal
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Adequate
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Sheep
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<
336
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336
to 500
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>
500
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<
280
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280
to 375
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>
375
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Cattle
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<
75
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<
75
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75
to 220
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>
220
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Consult
your veterinarian as to the response to vitamin B12
supplementation you could expect on your farm.
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| Preventing
cobalt/vitamin B12 deficiency |
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Increasing
cobalt intake by application of cobalt in the fertiliser
can prevent cobalt deficiency in grazing animals although
repeat applications may be required in a season making this
a costly method.
The direct treatment of grazing animals with cobalt is difficult
and labour intensive as large weekly or fortnightly oral
doses are needed. Intraruminal cobalt bullets can be effective
if they are not regurgitated or coated with ruminal contents.
Injecting vitamin B12 has been used
for many years as a means of protection against Cobalt/vitamin
B12 deficiency. While widely used,
injections of vitamin B12 preparations
at a rate of 0.05 to 0.1 mg vitamin B12/kg
liveweight have been shown to only be effective for up to
4 to 6 weeks.
Now, with SMARTShot, there is a simple cost-effective
way of providing your stock with the beneficial effects
of vitamin B12 over a sustained period.
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