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As the calving season approaches, the cows will show
typical signs that will indicate parturition is imminent. Changes
that are gradually seen are udder development, or making bag and the relaxation
and swelling of the vulva or springing. These indicate the cow is
due to calve in the near future. There is much difference between
individuals in the development of these signs and certainly age is a factor.
The first calf heifer, particularly in the milking breeds, develops udder
for a very long time, sometimes for two or three months before parturition.
The springing can be highly variable too. Most people notice that
Brahman influence cattle seem to spring much more than does a Holstein.
Typically, in the immediate 2 weeks preceding calving, springing becomes
more evident, the udder is filling, and one of the things that might be
seen is the loss of the cervical plug. This is a very thick tenacious,
mucous material hanging from the vulva. It may be seen pooling behind
the cow when she is lying down. Some people mistakenly think this
happens immediately before calving, but in fact this can be seen weeks
before parturition and therefore is only another sign that the calving
season is here. The immediate signs that usually occur within 24
hours of calving would be relaxation of the pelvic ligaments and strutting
of the teats. These can be fairly dependable for the owner that watches
his cows several times a day during the calving season. The casual observer
or even the veterinarian who is knowledgeable of the signs but sees the
herd infrequently cannot accurately predict calving time from these
signs. The relaxation of the pelvic ligaments really can not be observed
in fat cows, (body condition score 7 or greater). However, relaxations
of the ligaments can be seen very clearly in thin or moderate body condition
cows and can be a clue of parturition within the next 12 - 24 hours.
These changes are signs the producer or herdsman can use to more closely
pinpoint calving time. Strutting of the teats is not really very
dependable. Some heavy milking cows will have strutting of the teats
as much as two or three days before calving and on the other hand, a thin
poor milking cow may calve without strutting of the teats. Another
thing that might be seen in the immediate 12 hours before calving
would be variable behavior such as a cow that does not come up to eat,
or a cow that isolates herself into a particular corner of the pasture.
However, most of them have few behavioral changes until the parturition
process starts. Source: Calving Management, OSU Extension Circular
E-906.
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