Lesson Plan Overview / Details
This lesson takes students through the delivery process of a calf and the potential problems along the way. During this lesson students are given a "mission" to determine the gestation lengths of various livestock species. After they complete the mission I share with them a veterinarian scenario of a calf delivery, we then discuss the stages of natural delivery including hormonal changes that take place, and the three stages of calving. The lesson then moves into several common delivery problems such as a large calf, hip-lock, backwards calf, twisted uterus. We then progress into care of a newborn calf, and students have the opportunity to demonstrate the correct placement of obstetrical chains on a calf.
- 1 class period
- 60 Minutes
California Career and Technical Education Standards
- ANR.D.D4.1 Understand animal conception (including estrus cycles, ovulation, and inseminati...
- ANR.D.D4.2 Understand the gestation process and basic fetal development.
- ANR.D.D4.3 Understand the parturition process, including the identification of potential pr...
- ANR.D.D4.4 Understand the role of artificial insemination and embryo transfer in animal agr...
- ANR.D.D4.5 Understand commonly used animal production breeding systems (e.g., purebred comp...
- ANR.FS.11.0 Demonstration and Application
California Academic Content Standards (Reinforced)
Objectives and Goals
- Identify gestation periods of various livestock species
- Understand physiological changes that occur prior to, during, and after delivery of fetus
- Describe presentation problems that commonly occur during delivery
- Demonstrate correct placement of obstetrical chains
Activities in this Lesson
- Student Mission - Hooks / Set
Before students enter the classroom place the "Student Mission" worksheet at each seat face down. As students enter the room remind them not to touch the paper at their seat.
Explain to students that the day is going to begin with a mission. Their mission is to find the gestation lengths of the species that are on the paper in front of them. The students will have 5 minutes to find the information and may use any classroom resource the teacher deems appropriate. (Internet, textbooks, hidden clues, etc.) This is a silent mission, the students may not talk to anyone else while on this mission. The student(s) that can correctly complete the most items will be rewarded with a piece of candy.
Be sure to allow only 5 minutes exactly for this mission. When the time is up, direct students back to their seat and instruct them to pass their paper to the right. At this point the teacher will share the correct answers by using PowerPoint Slides #2-3.
Determine which student(s) has completed the chart most correctly and reward them.
- Parturition slide show [ Download ] Presentation to be used with all parts of lesson.
- Veterinary Log - Hooks / Set
Read the following excerpt from a veterinary log to the class.
“Most cows are able to calve on their own. When there is difficulty, most farmers are capable of assisting the cow with the delivery. When that fails, they call the veterinarian for help. One notable calving call came three years ago. The farmer told me that she had reached into the cow in an attempt to determine the problem. She told me that she was confused, because all she felt was this "thing."
Now I was confused. Her description did nothing to tell me what she was touching when she reached inside the cow. I drove to the farm, wondering what I was going to find. Even someone with limited experience is able to tell me if they can feel a hoof or a nose. This caller did not recognize anything she was feeling. I cleaned the cow and reached through the vulva and into the uterus. I have helped with hundreds of calvings, so I was confident that I could explain what was occurring. As my hand finally reached the calf, my first impression was exactly the same -- all I felt was this "thing."
She was right; it did not feel like a hoof, a nose, a rump or a back. I had to investigate more thoroughly. Reaching in as far as my arm could go, I was able to feel more parts. Unfortunately I now knew what had happened, but I also knew that I was in for a lot of work. I was finally able to feel a leg, but I also felt loops of intestine and a heart! When I felt the heart, I knew that the calf was inside out. This calf had a condition called schistosomus reflexus.
Display slide #4.
The deformity of the calf prevented a natural delivery. With the assistance of the farmers, I performed a Cesarean section -- surgical removal of the calf from the cow. We removed the calf through a large surgical incision on the left side of the cow. The cow stood through the entire procedure.
It is difficult to explain what the calf looked like. The calf was basically turned inside out lengthwise. Instead of the legs pointing downward from the spine, they were pointing upwards. The skin was folded upwards as well and the internal organs were all exposed. The calf was dead at birth, but the cow did well and actually bred back to have a normal calf the next lactation.”
The above excerpt is obviously a rare occurrence. We are now going to look at the various aspects of parturition.
Now display slides 5-8 and not the important aspects of each picture including presentation.
- Direct Instruction - Lecture
Successful calving is essential for cattle producers. Calves are the source for replacement animals for the herd and the source of a marketable product for the producer. Six to ten percent of all calves born in beef cow herds in the U.S. die at or soon after birth. Approximately half of those deaths are due to calving difficulties. This multi-million dollar annual loss is second only to losses from cows failing to conceive.
Display slide #9.
There are several hormonal changes that take place as parturition approaches. Progesterone levels decline and estrogen levels increase. The increase of estrogen levels prepares the uterus for delivery. The fetus releases a hormone called cortisone. This hormone stimulates the beginning of the birth process. Parturition or delivery of the newborn occurs normally at a point when the fetus is capable of surviving on its own.
Display slide #10.
Normal calving is divided into three general stages. Those stages are preparatory, fetal expulsion and the expulsion of the placenta or afterbirth. The time interval of each stage varies among types and breeds of cattle and among individuals of the same breed.
Display slide #11.
The preparatory stage will last from two to six hours. During pregnancy, the fetal calf is normally on its back. Just prior to labor, it rotates to an upright position with its forelegs and head pointed toward the birth canal. This position provides the least resistance during birth. Toward the end of gestation, the muscular lining of the dam's uterus increases in size, this aids in delivery of the calf. In the preparatory stage, the cervix dilates and rhythmic contractions of the uterus begin. Initially, contractions occur at approximately -minute intervals. As labor progresses, they become more frequent until they occur every few minutes. These contractions begin at the back of the uterine horn and continue toward the cervix, forcing the fetus outward. Any unusual disturbance or stress during this period, such as excitement or even movement, may inhibit the contractions and delay. At the end of the preparatory stage, the cervix expands allowing the uterus and vagina to become a continuous canal. A portion of the placenta (water sac) is forced into the pelvis and aids in the dilation of the cervix. This water sac usually ruptures and the membranes hang from the vulva until stage two.
Display slide #12.
Stage two or the delivery stage should last one hour or less. This stage begins when the fetus enters the birth canal, and usually occurs while the cow is lying down. Uterine contractions are now about every two minutes and are accompanied by voluntary contractions of the diaphragm and abdominal muscles.
Surrounded by membranes, the calf's forelegs and nose now protrude from the vulva. After the nose is exposed, the dam exerts maximum straining to push the shoulders and chest through the pelvic girdle. Once the shoulders have passed, the abdominal muscles of the calf relax, and its hips and hind legs extend back to permit easier passage of the hip region.
The calf is normally born free of fetal membranes (placenta), because they remain attached to the cotyledons or "buttons" of the uterus. This insures an oxygen supply for the calf during birth. Upon passage through the vulva, the umbilical cord generally breaks, and the lungs become functional.
Delivery is normally completed in one hour or less. Special assistance is warranted if this stage goes beyond two to three hours.
Display slide #13.
The final state is the cleaning. The caruncle-cotyledon, or button attachment between uterus and placenta, relaxes and separated after parturition. The placenta is then expelled by continued uterine contractions. Cows normally expel the placenta within two to eight hours.
These three stages are considered normal for most cows. Heifers may vary in length and actions during some of these stages as they tend to be more nervous. However, whether working with a heifer or cow, if the stages are severally out of place or not progressing, assistance may be needed.
- Me You Us E-moment - Assessment
You may check for student understanding by using the Me-You-Us E-moment.
Ask students to silently think about why the calf is normally born without the placenta covering. Tell stduetns they are going to have a moment to think abbe their answer.
Ask students to turn to the person to the their left and dicuss the answer. (Allow about 1 minute for discussion) Then ask one or two groups to share their answer witht he class.
- Me You Us Moment [ Download ] Me You Us Moment Instructions
- Malpresentations Lecture - Lecture
About five percent of the calves at birth are in abnormal positions, such as foreleg or head turned back, breech or rear end position, sidewise or rotated, etc. This requires the assistance of a veterinarian or an experienced herdsman to position the fetus correctly prior to delivery. If fetal position cannot be corrected, the veterinarian may have to perform a caesarean section.
Display slide #14-15.
Preparing for Calving Assistance
Normal delivery should be completed within two to three hours after the water sac appears in heifers, and one to two hours in cows. If prolonged, the calf may be born dead or in a weakened condition.
Since timing is vital to providing proper assistance, frequent observations are a must. Assisted deliveries should not be attempted without proper preparation of facilities and equipment. A clean, well-lighted maternity stall with head catch facilitates examination. Clean pulling (OB) chains and handles should be placed in a bucket of water with disinfectant before use to reduce bacterial contamination.
Disinfectant, soap and lubricant should be in plastic squeeze bottles to enhance use.
Check with your veterinarian for advice on when to assist a cow alone and when to call him. Experience will help determine if the calf can be delivered with assistance or if a caesarean is necessary. Determination is usually made on initial examination. The goal is to deliver a live calf from every cow.
Steps in Calving Assistance
Display slide #16.
- After observing a delay in delivery, a pelvic examination should be done to determine the extent of cervical dilation. The cow's vulva and rectum should be scrubbed, in addition to your hands and arms, and a plastic shoulder length OB sleeve worn.
- Determine the position of the fetus. If it is in an abnormal position, experience and judgment must be used to determine if a correction can be made or if professional help should be summoned.
Display & Discuss slides #17-19.
Display slide #20.
- Examine the size of the calf relative to the birth canal. A large calf forced through a small pelvic opening may result in death of the calf and injury (including paralysis) to the cow. If this examination is made when the head and front feet are still in the birth canal, the opportunity for a successful caesarean section exists.
Display slide #21
- Attach the obstetrical (pulling) chains to the front legs of the calf, placing the loop of each chain around each leg. Then slide the chains up on the cannon bone two to three inches above the ankle joints and dew claws. Make sure the chain pulls from the bottom of the leg (dew claw side).
Display slide #22
- Attach the obstetrical handles and pull gently, making sure the chains have not slipped. Although some calves can be delivered by pulling both legs evenly, it's usually best to alternately pull on one leg and then the other a few inches at a time. This is called "walking out the shoulders."
Display slide #23
- Once the head and shoulders are exposed, pull the calf downward at a 45° angle, or nearly parallel with the rear legs of the cow. This tends to raise the calf's hips and lessens the chance of hip lock.
- "Hip lock" can be a problem serious enough to cause loss of the calf. If this happens, push the calf back a short distance and rotate the calf a half a turn and pull downward and forward between the cow's legs. If the cow is lying down, roll her on her back and pull the calf forward over the udder between the hind legs. Make sure the calf begins breathing normally as the umbilical cord will be pinched closed. Call your veterinarian if the hip lock cannot be readily delivered.
- Posterior presentations (backwards calf) occur in less than five percent of calves born. The posterior presentation is a problem because the calf's hind legs and hips do not dilate the cervix as well as the front legs and head. Due to premature rupture of the umbilical cord, early assistance and rapid delivery is needed. A backwards calf in the setting position with feet and legs up under him (breech presentation) must be detected early in labor and corrected. Cows will start labor but nothing will show externally except occasionally the tail of the calf. If not detected, labor will cease and will not start again until the calf is emphysematous three to seven days later.
- Cows with torsion of the uterus (posterior uterus and cervix twisted) will act similar to cows with a breech presentation; however, they will usually show much more pain. On examination, the calf is difficult to palpate and the twisted opening can be determined. If detected early, the torsion can be corrected or a caesarean performed to obtain a live calf.
- A calf puller should be used correctly and only by experienced people. A calf puller can apply traction equivalent to the pull of seven men. First examine the cow, making sure the calf is in the proper presentation and position, lubricate the vagina, and then apply gradual traction. If no progress, a caesarean may be needed. Excessive traction may kill the calf, traumatize the cow and both may be lost.
Display slide #24.
- Correcting abnormal presentations and positions after extended labor usually requires professional help. Remember: be clean, learn your capabilities and learn when to call for help.
- Closing Activity - Closure
Review briefly with students the three stages of a normal delievery. Ask students to demonstrate (Using their arms) what a normal prenestation of a calf should look like.
Thank students for a great day!
- Assessment Types:
- Demonstrations, Observations,
Students will demonstrate the correct use of obstetrical chains. 2 small boards work well as the calf legs. You can also have students verbally explain what they are doing to reinforce the concept.