Material edited from the Calving Management Manual by Robert Mortimer MS, DVM, Colorado State University, Dept of Clinical Sciences
Always determine if the calf is in a normal presentation, posture and position. If the calf is not in the correct position or posture at the examination, then these must be corrected before beginning to pull. For instructions on this topic see the next section.
After examination and a determination that the calf is in the correct position and posture, chains should be placed on both limbs. They may be placed either above the fetlock joint or below the fetlock above the hoof of the calf or a combination of the two. In most instances, it is recommended to place the chains above the fetlock and take a half-hitch below the fetlock joint as well. The chain above the fetlock should be placed where the bone is decreasing in size on the leg above the growth plate of the bone.
Have the cow on her right side. It is easier to pull the calf when the cow is on her right side and the calf is lined up with the birth canal. Also, when the cow is lying down, she can push with each contraction and help deliver the calf.
Be sure you are in an area large enough for the cow to safely and comfortably lie down.
An example of casting the cow:
Another way to cast the cow is:
Take a long rope that has a honda at one end and place the rope around the flank of the cow. Put the one end through the honda and pull tight. Be sure that the rope is in front of the udder. Pull the rope in the direction you want the cow to fall.
You are now at a point to determine if delivery by forced extraction is possible. This test for delivery is valid only if certain criteria are followed relative to position of cow, type and amount of traction, and direction of pull. Traction should only be applied when the cow is assisting with an abdominal press.
Whenever the birth canal is evaluated, and during the entire process of calving assistance, it is extremely important to maintain excellent hygiene. The operator's hands and arms and the cow's vulva and surrounding area must be cleaned and disinfected repeatedly. Clean/sterile lubricant should be used liberally and frequently. During attempts to pull the calf, the birth canal should be dilated using your hands and forearms.
To repeat - for any of the assistance procedures it is
extremely important to:
Always manually dilate the vulva for at least 5 minutes.
Delivery of the Frontwards (Anterior) Calf by Forced Extraction
In the frontwards presentation with normal position and
posture of the fetus, the guideline is whether both shoulders of the calf
can pass through the pelvis of the cow using recommended traction techniques.
To actually determine this, the cow should be down, on her right side,
and traction should be applied to one leg at a time (unilateral traction)
to walk the shoulders through the pelvis of the cow. Positioning of the
cow on her right side allows the frontwards calf to enter the pelvis of
the cow relatively straight. In a difficult delivery this is important.
Once the first shoulder is through the pelvis of the cow, it should be held in place and traction applied to the other leg. The amount of traction should be limited to the force of one strong person per leg. Two strong people can exert a force of from 400-600 pounds while erroneous use of a fetal extractor could exceed 2000 pounds of pressure.
Using the force of two people (one on each leg of the calf).
Pull one leg at a time
If both people pull at the same time the elbows of the calf will lock up against the pelvis of the cow making it difficult the deliver the calf.
The pressure exerted by two people pulling is about 400 psi
The pressure exerted by a calf jack can be as much as 2000 psi if used imporperly.
Good clinical judgment in the application of traction is important and necessary. Our goal is to deliver a live calf with the maximal opportunity for survival. Exceeding this rule may result in the delivery of the calf, but will markedly increase the chances for the loss of the calf during delivery or subsequently to disease, cold, or starvation. The direction of pull should be straight back from the cow, which is difficult unless the cow is down.
Rotating the calf will allow the hips to line up better with the pelvis of the cow making delivery of the hips easier.
Once breathing has been established, completion of delivery is possible in most instances. Occasionally, calves are lost because of failure to allow the calf to breathe. Constant pulling on the calf at this point will not allow the calf to expand its chest and take in any oxygen and it is possible to lose the calf if breathing is not allowed.
Delivery of the Backwards (Posterior) Calf By Forced Extraction
The test for delivery of a calf in the backwards presentation but normal position and posture differ because the fetus should be FIRST rotated 45-90 degrees by crossing the legs before attempting delivery to take advantage of the widest diameter of the cow's pelvis.
In addition, the direction of pull on the calf is in a
direction that is slightly up from a line straight out from the back of
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