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Improving heat detection
For good heat detection there must be:
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Clear identification of cows by freeze
branding or easy to read ear tags.
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Adequate light to ensure cows can be
seen in heat and identified.
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Regular oestrus observation. Try to set
aside three periods of 20 - 30 minutes
throughout the day that are not associated
with feeding or milking for heat detection.
Most mounting activity will take place
between 6pm and 6am so it is important
to observe cows during this period.
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A good recording system, either
computerised or manual with all heats
recorded including those before the
service period.
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Adequate loafing areas with nonslip
floors to allow cows to exhibit normal
oestrus behaviour.
Heat detection may be further
improved by using:
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Heat mount detectors.
These are stuck on
the cow’s back, on the tail head and are
triggered by the pressure of another cow
mounting them, leading to a colour
change. Examples of these are Kamars™,
Bovine Beacons™ or Estrotect™.
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Tail paint.
This works by a similar
principle to above with paint rubbed
off by mounting behaviour. Tail paint needs
to be reapplied when it becomes dry
and cracked.
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Motion detectors/pedometers.
These are
attached to either the neck or leg bands
respectively and any increases in walking
activity are remotely detected and
recorded on a computer. These can be
very useful, but care must be used in
interpreting them as there may be other
reasons for increased activity.
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Regular milk progesterone assays.
To
detect the fall in milk progesterone prior
to oestrus. On-farm kits are available,
but will only become practical on a
large scale when in line detectors
become available.
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Synchronisation.
Groups of cows can be
synchronised with hormone treatment to
allow fixed time AI.
There are various hormone treatments
available for cows with ovarian cysts and
those that are anoestrus ('not cycling').
In some herds it may be appropriate to
use hormone regimes to allow fixed time
AI or to allow compacted periods of
heat detection.
An example of this is the Intercept ™
regime which involves the use of injections
of prostaglandin and GnRH. Another
option is the use of PRIDs or CIDRs. There
are several options and the best one for
your herd can be discussed with your vet.
F A C T F I L E
SPRING 2010 ISSUE
LIVESTOCK MATTERS
6
An Estrotect heat mount detector with the silver
surface well scratched off indicating she is likely
to be in heat.
A cow wearing a pedometer to aid
heat detection.
COS T OF D I S E A S E
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There are various figures quoted for
the costs of an extended calving to
conception interval. The relative cost
per day increases the longer the
interval. This cost calculated using
extra feed costs loss of milk yield
and increased veterinary costs.
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The cost rises from £2.47 per day
with a month’s delay to £6.52 per
day for 5 month’s delay. (DAISY
Research Report No.5)
Regular examination of cows that are
either not seen bulling, that have short
cycles or prolonged bulling behaviour
allow for the identification of follicular
or luteal ovarian cysts, or anoestrus and
allows prompt treatment by a vet before
too much time is lost.
THE OESTRUS CYCLE
This shows the waves of progesterone
and oestrogen, with the cow being in
heat during the surge in oestrogen.
If the cow does not become pregnant
this is repeated. If she is pregnant the
progesterone level remains high.
“After calving cows will begin to cycle after
20 to 30 days. This may be extended in high
yielding cows or those affected by disease
post calving”