Calving is a continuous event but for explanation it is divided into 3 stages.

• Stage 1
  This stage, lasting 2-6 hours (can be a couple of hours longer in heifers), begins with initial labor and ends when the cervix is fully dilated and the calf has entered the birth canal. The end of stage 1 is marked by the observation of the water sac. The cow may show signs of discomfort by kicking at her belly, and becoming restless due to contractions. She may separate herself from the rest of the cows and urinate frequently. These signs are especially evident in heifers.
  

• Stage 2
  In this stage, that lasts 1-2 hours for cows and 2-4 hours for heifers, the cervix is fully dilated, the cow may lie down, contractions will increase and abdominal pushing is obvious. This stage ends with delivery of the calf.
  

The calf must enter the birth canal in a certain position in order to have a normal delivery.

The terms presentation, position, and posture are used to describe how the calf is positioned in the birth canal. It is important that everyone on your operation dealing  with calving have a basic understanding of these terms in order to communicate with each other and with your veterinarian in cases of dystocia.

Presentation refers to whether the calf is coming forward (anterior) with both front legs and head extended into the birth canal, backwards (posterior) with both hind legs extended into the birth canal (soles of the hooves up and toes pointed down), or transverse with either all four legs in the birth canal or the back of the calf entering the birth canal. Both forward and backward presentations are considered normal with forward being the most common. Keep in mind that a backward presented calf is a high risk calving because the umbilical cord is pinched off before the calf's head is delivered. A transverse presentation is never normal.

     


Position refers to how the calf is positioned in relation to the cow. If the calf's back is up towards the cows back (spine) it is considered right-side up (dorsal). This is the only position that is considered normal. If the calf's back is down on the bottom of the pelvis it is upside down (ventral). The calf may also be on either of it's sides; right-side down or left-side down.



Posture refers to where the calf's limbs and head are in relation to it's body. The limbs and head should be extended into the birth canal. If the head or one or both of the limbs is retained the calf is considered malpositioned and needs to be adjusted prior to delivery.



The picture above is looking down onto the calf as if you are above the cow.

The most common delivery is when the calf is in a frontward presentation, a right-side up position, and with both front limbs and head extended into the birth canal.

You will observe that the cow will have strong abdominal presses while delivering the head and chest of the calf, after which she will usually take a short break (5-10 minutes or less). During this time the umbilical cord is being pinched off and you should notice the calf begin to breathe on it's own. After the short break, the hind limbs should be delivered uneventfully.

The water sac that is surrounding the calf's head should break during delivery of the head. If it does not break the calf could suffocate.



• Stage 3
  After the birth of the calf, the placenta should be delivered within 6 hours.