A new calving season is upon us, and as a veterinarian, I get numerous calls (not all of them during daylight hours) to advise or assist with delivering calves. These are some basics that every cattle producer should be aware of so that successful delivery of a live calf is achieved.
It is well documented that death loss during calving is a leading cause of decreased numbers of weaned calves per cow, second only to cows failing to become pregnant.  So knowing when to check a heifer or cow and when to assist with delivery is important.  The first thing to understand is the stages of labor.  In Stage 1, the animal is uneasy, moves away from the group, gets up and down frequently, and displays signs of “colic,” such as kicking at her side and arching her back.  The time this stage lasts is quite variable, from one to two hours to several hours.
Stage 2 labor begins when the calf’s feet move into the pelvic canal.  The water bag and the feet will appear at the vulva soon thereafter, and the water bag will break soon after its appearance as abdominal and uterine contractions increase in strength and frequency.  Pressure from the calf’s legs and head in the pelvic canal send hormonal signals to the cow that release oxytocin and result in stronger uterine contractions occurring at a rate of two to four contractions every five minutes.   Stage 2 may last as little as 15 minutes.  I expect this stage to take two hours at the very most in a normal delivery.  Several studies indicate that heifers generally take approximately twice as long to deliver as cows.
Stage 3 begins after birth and concludes with expulsion of fetal membranes or afterbirth.  Normally this occurs within 2 hours of birth, but is generally complete within 24 hours.
So, when should you intervene and assist?  My rule of thumb: after the water bag breaks, give one hour for a heifer and one-half hour for a cow before you examine the animal to assess progress.  If steady progress is being made, continue to check at least every 30 minutes.  If no progress is made within 1 hour, assistance is needed.
When you check the animal, first determine the position of the calf.  The front feet and the head should be in the pelvic canal in a normal presentation.  Any other presentation is abnormal; work with your veterinarian to learn how to determine how the calf is positioned.  Unless you are trained or comfortable repositioning the calf, your veterinarian is the best trained person to assist delivery.  If you assist delivery yourself, clean the cow and your hands and arms with soap and warm water.  This is not a sterile environment, but it should be made as clean as possible.
The next question you need to answer once you determine the calf is in a position to deliver is “How hard do I pull?”  DO NOT call your vet AFTER you have driven a steel post behind the cow and hooked the calving chains or ropes to the bumper of the truck and popped the clutch.  Always try to deliver by hand with calving chains or ropes looped around the calf’s feet above the fetlock.  I recommend a second loop below the fetlock to decrease pulling force on the leg.  This will decrease the chance of fracturing a leg during delivery.  Another good rule of thumb is to apply no more pressure than can be generated by two men pulling by hand.
A calf puller can be a valuable tool to help delivery in the hands of someone trained to use one properly.  It can also kill animals when used incorrectly.  Be patient, and go slowly to allow the tissue in the cervix, vagina, and vulva to stretch.  Also, use liberal amount of OB lube to facilitate delivery with the least trauma to the cow or heifer.
Remember, the goal should be to deliver a healthy calf that has a healthy mother to raise it. This requires patience and a watchful eye.  I can’t over-emphasize that training in the proper methods of examination and delivery is vital to successful assistance.    
Good luck this calving season.
Mike Bloss, DVM, owns Countryside Animal Clinic with his wife, Kristin Bloss, DVM, in Aurora, Mo.

AdministratorOn-Call / VetMissouri,On CallA new calving season is upon us, and as a veterinarian, I get numerous calls (not all of them during daylight hours) to advise or assist with delivering calves. These are some basics that every cattle producer should be aware of so that successful delivery of a live calf...The Ozarks' most read farm newspaper, reaching more than 58,000 readers in Missouri, Arkansas and Oklahoma