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X LV E T S SCHOL AR SH I P
SUMMER 2010 ISSUE
LIVESTOCK MATTERS
22
Given that pasture feed isn't a hundred
percent reliable, farmers have to be very on
the ball with regard to condition scoring their
cows. I have been out to do a few herd
condition scores as many farms do this
quarterly. If the cows are not in good
condition for service, this can have a huge
effect on the in-calf rates. Manipulating
condition is most easily done at the end of
their previous lactation. Cows are most
efficient at gaining condition whilst they are
still lactating however they need to be fed
sufficiently at this time to achieve this. As
most New Zealand cows are not fed large
amounts of supplement, and at this time of
year (autumn) pasture growth has slowed, it
can be difficult to give them the feed they
need whilst lactating. Therefore it is often more
cost effective for farmers to dry off cows of
a poorer condition score early or to cut them
back to once a day milking, rather than
supplement feed them. This is just one example
of where keeping feed costs down is more
important than increasing milk production.
Managing pastures here is done extremely
accurately as keeping the pasture, often the
only food source, in good condition is almost
as important as the cow. Pastures are grazed
down to specific residuals (eg 1500kg
DM/ha) even if this requires putting cows out
only for 1-2 hours on to one pasture after
milking before having to move them to the
next, in order to maintain pasture quality.
Maintaining good quality pasture is vital to
the success of the grazing season and during
the growing season pastures are measured
with a plate meter every 5-7 days. Most
intensively grazed pastures are made up of
perennial ryegrass and clover. Managing
pasture quality is also important to avoid
diseases such as nitrate poisoning, ryegrass
staggers and frothy bloat.
Most cows calve from July to September just
as the grass starts to become available, so
the majority of scanning is done from
February to April. Scanning is usually done
during a milking, as the experienced
scanners can manage about 300 cows an
hour in the rotaries. Most farms use AI initially
and follow up with bulls. Many cows that get
in calf after 8-9 weeks of service will be
induced (banned in the UK) in order to keep
calving patterns tight. Good farms will aim
for a 90% conception (in-calf) rate for the first
9 weeks, and they try to keep induced cows
down to fewer than 10%. There are a
number of ethical issues associated with
inducing cows before the calf is viable, and
so there are strict rules in place regarding the
timing of induction so that no calves should
be born dead. Therefore we need to age
the pregnancies to determine which animals
should be induced and when. Herds using
inductions will have an initial scan for the first
6-9 week pregnancies then another 6 weeks
after this to determine animals suitable for
induction, and then they may have a final
scan to figure out the empties. It is much easier
and quicker to age pregnancies at 6-8 weeks
so we try to scan most when the cut off for
inductions are around this stage of gestation.
Few hormonal treatments are used currently;
however this may change if inductions are
banned. Some use prostaglandin and/or
progesterone to bring on their non-cyclers
early on in the mating period.
Heifers are also scanned at this time. Most
people will calve their heifers a couple of
weeks before the rest of the herd. They aim
for a <4% empty rate in the heifers using just
over 1 bull per 20 heifers. We find the
biggest factor affecting empty rates is getting
the flush of feed at the right time, so they are
on a rising plane of nutrition when they are
served. Most farmers weigh them regularly
from birth to make sure they achieve this.
Bull problems and diseases such as BVD
also affect heifer conception rates.
From a vet's animal health perspective, my
initial view was how rosy dairying seemed
out here. The cows were out in the sun,
grazing lush green pastures and looked great
on their low input low output system.
Lameness and nutritional diseases such as
acidosis and displaced abomasums are a
rarity, and being an isolated island in the
Pacific, New Zealand also has the luxury of
being free from many of the diseases that we
deal with every day in the UK. However
after a few weeks of work and chatting to
the local vets and farmers I am beginning to
realize they have their own different sets of
problems. Major production diseases like
Johne’s and BVD are pretty commonplace
and control measures seem to have been
fairly lax in the past, although slowly
awareness is improving. There are also a
whole set of problems associated with
pasture which occur far more commonly over
here; various toxicities, bloat, trace element
deficiencies and photosensitization. I also
think winter may change my opinion
somewhat; if it is tough, cows outside can
suffer hugely especially as they calve down
at the coldest and wettest time of year with
no housing whatsoever to protect them from
the elements. When problems occur they
tend to happen in outbreaks as all cows are
at the same stage so I expect my view in a
few months time may be slightly different.
NEW ZEALAND
TRAVEL SCHOLARSHIP
Amy Avery
Endell Veterinary Group
Mark Spilman
Bishopton Veterinary Group
Nicola Fair
Lambert, Leonard & May
Joe Davis
Torbridge Veterinary Hospital
T
he first four people to be awarded the
XLVets New Zealand Dairy Travel
Scholarships are:
The scholarship programme provides
recipients with help from members of
The Society of Dairy Cattle Veterinarians
(DCV) of the New Zealand Veterinary
Association to find suitable dairy practice
employment in New Zealand.
As part of their scholarship the candidates
work in New Zealand and then receive
an additional bursary for taking up
employment with an XLVets member
practice on their return to the UK.
Updates on their progress will be featured
in future issues of the magazine.
XLVets would like to thank the
DCV for their support with this
SCHOLARSHIP SCHEME.