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X LV E T S SCHOL AR SH I P
I
n this issue we feature the second part of the report from Joe Davis on
his experience in New Zealand. Joe gives us an insight into the work
he undertook in Southland.
XLVets New Zealand
Dairy Scholarship 2009/10
Joe Davis
XLVets New Zealand scholar
THE JOB
Calving
One of the major differences between
working in New Zealand and working in the
UK is the seasonal nature of the work. At
home you can expect a calving from the
depths of winter to the height of summer, in
NZ most farms would expect to see three
quarters of their cows calve in a 6 week
block in spring with the rest following in the
next 2 months. As a vet this means that you
are calving cows and treating metabolic
problems such as hypocalcaemia all day
every day for a concentrated period. The
calving pads or paddocks are awash with
calves and cows calving, unfortunately, this
can lead to the incorrect identification of
calved cows and the odd cow with
dystocia being missed.
Metabolic problems around calving are a
constant battle. It's hard to get enough
magnesium into the grazing cows at high risk
of milk fever and hypomagnesaemia with
little opportunity for even a partial DCAB
diet. Magnesium chloride and magnesium
sulphate are provided via the water supply
from a central dosing system. This provides
the calculated daily dose of supplements to
the water supply over the day irrespective of
variations in water intake. Magnesium oxide
is commonly dusted over the grass prior to
grazing, or, poured on top of any baleage
being fed in order to provide even more
magnesium without causing the drinking
water to become unpalatable.
Disease
BVD is high on the agenda in New Zealand.
Bull testing and vaccination is commonplace
and with the introduction a bulk milk test for
the virus which is sensitive enough to pick up
one infected cow in a bulk tank of milk from
1,000 cows, tracking down persistently
infected animals has become a lot simpler.
Johne's disease, however, doesn't seem to
worry most farmers. I find this surprising as
the New Zealand system puts youngstock at
high risk of infection. Use of a calving pad
where calves come into contact with the
faeces from a large number of cows and the
use of bulk colostrum from fresh calvers are
both potentially dangerous practices. Even
though the disease still has low prevalence
by UK standards it could cause major
problems for the industry in the future.
Minerals
Many New Zealand soils are naturally
deficient in cobalt, selenium and copper but
high in molybdenum. Reliance on brassicas
for dry cow feeding can also lead to
deficiencies especially in iodine and copper.
It is necessary to keep a close eye on cow
mineral levels throughout the cycle to prevent
problems occurring. A part of my work was
to take liver biopsies and blood samples as
part of the VetSouth 'Production Profile PLUS'
scheme. Samples are taken pre-calving,
pre-mating and pre-drying off. The liver
biopsies give an insight into liver stores of
copper and the bloods reveal magnesium
and selenium levels. Using the biopsy needle
for the first time is slightly nerve-wracking.
Poking a one foot long stainless steel rod
through the cow's diaphragm to embed in
her liver without any ultrasound guidance
seems initially wrong but the cows deal with
it well and you can be surprisingly accurate
with the needle. Deficiencies are addressed
by drinking water supplementation for the
milkers and a combination of long acting
injections and boluses for the dry cows
away at keep.
Other cases I attended included several cows
with photosensitization, a couple of cows
with squamous cell carcinomas of the eye or
'cancer eye' (these both needed removal of
the eye to stop the cancer spreading), and
various other more run-of-the-mill ailments.
I did get a call to a fawning one weekend,
my deer knowledge is minimal so I adopted
the 'treat it like a large, highly excitable
sheep' approach and with the help of a
healthy dose of sedative, the fawn was
successfully extracted.
WINTER 2010 ISSUE
LIVESTOCK MATTERS
24
A rare Holstein at Gore Show