Ketosis in cattle

Ketosis in cattle

November 4, 2019 1 By William Morgan


(UPBEAT COUNTRY MUSIC)
Over the last few years,
cattle producers
in the West Midlands
have been reporting problems
with pregnancy toxaemia, or ketosis,
in the cow herd.
We’d like to use this presentation
to discuss
some of the causes of ketosis
and to discuss
some of the strategies
that cattle producers can adopt
to reduce this problem.
Cows have a high energy
requirement
in late pregnancy and early lactation,
when the energy requirement’s
not being met by the nutrient intake,
the cows start to break down
their own body reserves
to meet the deficit.
If the rate of breakdown of the fat
is too fast,
then toxic waste from
the breakdown process accumulate
and cause the signs
associated with ketosis,
which the cows get disorientated,
they stop eating,
they might go down
and gradually go into a coma and die
if treatment is not begun early.
Cows with damaged livers
or reduced appetite
are most susceptible to ketosis.
There are two fairly common
pasture plants in the West Midlands
which can cause liver damage –
the pasture legume blue lupins,
when it is affected
by the fungal toxin phomopsin,
and the pasture species
Paterson’s curse.
Fortunately, the cause of the liver
damage can be diagnosed
by post-mortem
and laboratory testing.
In 2011, there were eight cases
of chronic liver damage
submitted to the Animal
Health Laboratories in South Perth.
These were differentiated
into four cases being contributed
to Paterson’s curse poisoning,
two cases diagnosed as lupinosis,
one case where both
Paterson’s curse and lupinosis
were associated
with the chronic liver damage,
and a single case of saponin toxicity
in some younger cattle.
The mortality in the herds
affected with ketosis
that were submitted to the laboratory
ranged from 1-2%.
Most of the cases were in cows
of more than four years of age.
The good news is that the liver is
one organ that is able to regenerate.
For example, if half the liver
is removed in a healthy animal,
the animal will have full liver
functional capacity within a month.
After an acute case of liver damage
where the cause is identified
and removed early,
the cattle have a good chance of
having full liver functional capacity
in 6-12 months.
However, if the liver is being
continually exposed to a liver toxin,
this results in the
cumulative damage to the liver
and an inability to recover.
The pasture weed Paterson’s curse
contains a toxic compound,
pyrrolizidine alkaloid.
This is present
in all parts of the plant,
including the stem and the leaf
and the flowers,
and it’s present in the green material
and in dry material,
including baled hay.
The toxicity increases at flowering
and when the plant is stressed.
After spraying, the palatability
of the plant increases
and also increases
the incidence of poisoning.
The pyrrolizidine alkaloid
damages the liver cells.
It damages the DNA of the liver cell
and it can damage the blood supply
to the liver cells.
The extent of this liver damage
and the fact that the plant is toxic
year-round
makes it hard
for the liver to regenerate
when cattle are grazing pastures
containing Paterson’s curse
for extended periods.
Blue lupins are a useful feed source
and fix atmospheric nitrogen.
However, after summer rain,
they may develop a fungal toxin,
phomopsis, on the stem
and cause a disease
known as lupinosis.
Sheep are more susceptible
to lupinosis than cattle,
however the sheep livers recover
more rapidly than cattle livers.
The phomopsis toxin
affects the liver cells
and it also suppresses appetite.
In late pregnancy,
cattle with a reduced appetite
are more susceptible to ketosis.
When cattle are grazing blue lupins
and have chronic liver damage
associated with lupinosis,
they may not be clinically affected,
but they probably will be a little
bit ill thrifty and fail to gain weight.
The livers can remain cirrhotic
for a long period of time.
However, they are generally
fully functional within 12 months.
When sheep have been affected
by lupinosis,
once they’ve recovered
and start to eat again,
those sheep
that have got to this stage
will normally regenerate quite well
within six months.
The best way of preventing ketosis
in cows
is to provide them a good source
of energy in late pregnancy
and early lactation.
Green pastures with at least
two tonnes of feed on offer
provide sufficient energy.
If the pastures
don’t have this much feed,
it’s important to provide
a good quality energy supplement.
This might be a high energy grain
or a very good quality hay.
If you know that your cows
have some liver damage
or you suspect they might have
from previous exposure to lupins
or Paterson’s curse,
then it is a good idea not to use
a high-protein supplement
such as lupins.
Also, in late pregnancy,
it’s important not to graze pastures
containing old blue lupin stalks
because if they do get some
lupinosis at this stage of pregnancy,
their appetite will be reduced
and they are more likely
to go into ketosis.
If there are some old blue lupin
stalks in the paddock,
the alternative is to provide
a really good, high quality roughage
so that they don’t eat the stalks.
It is most important
that if producers have
Paterson’s curse in their pastures,
they aim to control it.
The plant is a weed
and doesn’t provide any value
to the pasture.
Blue lupins, on the other hand,
provide a good feed source.
They put nitrogen back into the soil,
and blue lupins can be grazed
strategically to avoid liver damage.
The sort of strategies
that you can adopt
is to remove cattle from blue lupin
paddocks after summer rain.
The cattle are more likely to eat
the stalks after summer rain
when they’re wet
and the other dry feed is also wet.
But gradually, over summer,
with incidences of summer rain,
the amount of phomopsin toxin
on the stalk will increase.
Also remember
that when you’re feeding cattle
in a blue lupin paddock,
it’s important that there is
an alternative roughage source
so they aren’t tempted to eat
the blue lupin stalks.
Cattle producers with a current
ketosis problem in their cow herd
associated with chronic liver damage
may wish to adopt a culling strategy
to reduce the problem.
What you can do is, prior to joining,
you can bring the cow herd in
and draft off the bottom 10%-20%
of the herd
and then do a blood test
on these cows
to assess the liver-functioning
capacity.
Or, because most of the cases
that we’re seeing of ketosis
are in cows
of more than four years of age,
you may wish to reduce the age
at which you cull your cow herd.
Adopting one of these
culling strategies,
in combination with controlling
Paterson’s curse on the property
and strategically grazing blue lupins,
should reduce the problem of ketosis
in your herd.