I WAS always told that you need
to experience the rainy season in
Southern Africa to appreciate the
volume of water that can drop out
of the sky.
Three inches of rain in one hour
is like someone turning on a really
powerful power shower. Immediately
afterwards the sun comes out and
everything
returns to
normal.
I work with
a group of
farmers in
Zimbabwe,
helping them
with mastitis
and milk quality issues and other
aspects of preventive medicine and
fertility. Milk price is the same as in the
UK and cell count penalties are just as
severe.
It is unusual for any cows to be
housed as the rainy season arrives in
November and ends in March. This
is the time that conditions at pasture
or in paddocks become extremely
challenging.
The level of clinical mastitis can
increase tenfold and at the end of the
rainy season herd cell count might have
increased to levels of 400 to 600.
Mud baths
Many of the larger intensive herds
keep their cows in paddocks which can
become like mud baths! It has to be
seen to be believed, and my last trip
coincided with the end of the rainy
season.
All mastitis bacteria enter through
the teat canal which is 6 to 10mm long.
It is the primary defence mechanism to maintain a semi-sterile udder and keep
bacteria out.
It has to open as wide as possible
during milking for a fast milk out and
we know that high-yielding cows have
more open teats with faster ow rates.
Some of the cows in Zimbabwe are
giving on 8,000 to 10,000 litres and so
the risk factors are high.
Any damage to the teat canal will
allow bacteria easier access to the
udder. When the teat canal closes it
is like a series of inter-digitating folds
that try to stop anything entering. It is
amazingly efficient.
However, when you encounter
overwhelming challenge of infection
like when cows are semi-submerged in
mud and manure, then these defence
mechanisms can fail. Cows love
submerging themselves as it is cool
and also very comfortable. They do
not think about the implications for
mastitis or anything else.
Many of these environmental
bacteria will enter the udder. The cow
will respond by pushing in millions of
somatic cells to try and eliminate these
bacteria. This results in a significant
increase in cell count in individual cows
and herd cell count.
Miracle
of nature
This cell count then subsides within 4
to 6 weeks after the end of the rainy
season. This really is a miracle of
nature as it shows just how effective
the udder immune system is at
stopping even more cases of clinical
mastitis occurring.
One of the most difficult challenges
is faced by the milkers. These cows
can enter the parlour in horrendous
condition. The milker’s job is to ensure
that teats are clean and dry before
milking.
Many of the parlours are tired
and in need of upgrade or replacing.
Some have poor vacuum stability,
poor pulsation and most do not
have automatic cluster removers.
Unfortunately, as Zimbabwe went
through hyperinflation which ended in
2008, money is nothing like as available
or as easy to access as in the Western
world.
This means that milking can be slow
and in the dry season a shift might
last 4 to 6 hours. Once milkers are
challenged with really dirty udders and teats, you can add a further two hours
on to milking.
The difficulty is that nobody can
focus on carrying out a good job for
this length of time and so the animals
that are milked rst will be cleaned
quite well, but those that come in
towards the end are likely to be less
well-prepared.
All of these factors add to the risk
of clinical mastitis occurring. Muck
and manure challenging the teats and
teat ends increases the risk of clinical
mastitis.
Many of our dairy clients have
made signifocant improvements to the
environment where their cows are
housed. One of our herds put in a
new 400-cow cubicle shed bedded on
sand and he has reduced mastitis levels
to between three and four cases per
month, equivalent to a mastitis rate of
15 cases per hundred cows per year.
Incredibly clean
There are other herds
running at similar levels, and
it is easy to see why this is
occurring as the udder and
teats are incredibly clean.
Unfortunately, there are
still many herds where the
environmental conditions
are very poor. In some of
these cases the mastitis rate
can be as high as 100 cases
per hundred cows per year.
This is pretty soul-
destroying for the milker,
creates a welfare issue
for the cow and, of
course, costs the farmer
a significant amount of
money in treatment and lost
milk.
The aim has to be to
keep cows in the cleanest
possible conditions to
minimise the risk of clinical
mastitis. My farmers in
Africa are now looking at
ways that they can provide
these conditions for cows
for the up-coming rainy
season this November.
They now understand why the
problem is occurring and what
action needs to be taken. While
their conditions are extreme, it just
highlights the importance of keeping
teats clean all year round to minimise
clinical mastitis.
- Peter Edmondson runs the Mastitis
Control and Quality Milk Production
Seminar with Roger Blowey which will
be held from 9th to 11th November in
Gloucester. Visit www.sheptonvet.com
for further information.
