Calving
The 3 Stages of Parturition in Cattle
By Glenn Selk, Oklahoma State University
As the spring calving season
approaches, an increased understanding
of the parturition process is helpful.
The more we understand about
the physiology of the process, the
more likely we are to make sound
decisions about providing assistance.
Parturition or “calving” is generally
considered to occur in three stages.
Stage 1
The first stage of parturition is dilation
of the cervix. The normal cervix is
tightly closed right up until the cervical
plug is completely dissolved. In stage
1, cervical dilation begins some 2 to
24 hours before the completion of
parturition (2 to 6 hours would be
most common). During this time the
“progesterone block” is no longer
present and the uterine muscles are
becoming more sensitive to all factors
that increase the rate and strength of
contractions. At the beginning, the
contractile forces primarily influence
the relaxation of the cervix but uterine
muscular activity is still rather quiet.
Stage 1 is likely to go completely
unnoticed, but there may be some
behavioral differences such as isolation
or discomfort. At the end of stage
one, there may be come behavioral
changes such as elevation of the tail,
switching of the tail and increased
mucous discharge. Also relaxation
(softening) of the pelvic ligaments near
the pinbones may become visually
evident, giving a “sunken” appearance
on each side of the tailhead. Checking
for complete cervical dilation is
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important before forced extraction
(“pulling”) of the calf is attempted.
Stage 2
The second stage of parturition is
defined as the delivery of the newborn.
It begins with the entrance of the
membranes and fetus into the pelvic
canal and ends with the completed birth
of the calf. So the second stage is the
one in which we really are interested.
This is where we find all of the action.
Clinically, and from a practical aspect
we would define the beginning of stage
2 as the appearance of membranes or
water bag at the vulva. The traditional
texts, fact sheets, magazines, and other
publications that we read state that
stage 2 in cattle lasts from 2 to 5 hours.
Data from Oklahoma State University
and the USDA experiment station at
Miles City, Montana, would indicate
that stage two is much shorter. In these
studies, assistance was given if stage
two progressed more than two hours
after the appearance of water bag at
the vulva. The interesting thing about
the data was that the heifers calving
unassisted, did so in about one hour
after the initiation of stage two, and
mature cows calved within an average
of 22 minutes of the initiation of stage
two. Those that took longer needed
assistance. These and other data
would indicate that normal stage two
of parturition would be redefined as
approximately 60 minutes for heifers
and 30 minutes for adult cows. In
heifers, not only is the pelvic opening
smaller, but also the soft tissue has
never been expanded. Older cows have
had deliveries before and birth should
go quite rapidly unless there is some
abnormality such as a very large calf,
backwards calf, leg back or twins. If the
cow or heifer is making good progress
with each strain, allow her to continue
on her own. Know your limitations.
Seek professional veterinary help
soon if you encounter a problem that
cannot be solved easily in minutes.
Stage 3
The third stage of parturition is the
shedding of the placenta or fetal
membranes. In cattle this normally
occurs in less than 8 to12 hours. The
membranes are considered retained if
after 12 hours they have not been shed.
Years ago it was considered necessary
to remove the membranes by manually
“unbuttoning” the attachments.
Research has shown that manual
removal can be detrimental to uterine
health and future conception rates.
Administration of antibiotics usually
will guard against infection and the
placenta will slough out in 4 to 7 days.
Contact your veterinarian for the proper
management of retained placenta.
An important ingredient for your calving
season preparation is the Oklahoma
State University Extension Circular
E-1006: Calving Time Management
for Beef Cows and Heifers. Cow calf
producers will want to download
this free circular and read it before
the first calf is born this spring. I