Anatomy of the Cow
What is Dystocia?
Dystocia is defined as a difficult or delayed birth at any stage of labor.
It is important to know the normal aspects of calving in order to determine if the cow/heifer is experiencing dystocia.
Causes of Dystocia
The causes of dystocia from many management choices ranging from breeding genetics and nutrition to management of the cow or heifer during delivery.
· Breeding - genetics can play a role in dystocia through birth weight and heifer development.
· Over conditioned dam - too much fat around the pelvis can lead to a small birth canal.
· Malformation of the calf or the dam.
· Shortened or lengthened gestation.
· Heifers often have dystocia because the birth canal (mainly the vagina and vulva) does not stretch enough for the calf to be delivered.
· Fetal-maternal incompatibility (the fetus is too large or the cow's pelvis is too small) - most frequent cause of dystocia in beef cows/heifers.
· Malposition - infrequent cause of dystocia; occurs in less that 4% of all calvings in beef animals, but may be more frequent in dairy animals.
· Other diseases - i.e. Milk Fever where there is a decrease in calcium which will decrease muscle tone causing the cow to become too weak to push out the calf, or uterine torsion where the cervix is twisted.
There are many things a producer can do prior to calving that will help decrease the amount of dystocia that he/she encounters during calving.
Preventive Measures to Decrease the Incidence of Dystocia
There are many causes of dystocia, some that can be prevented and others that cannot. Many times there may be multiple causes involved in an individual dystocia incident. Even with all preventative measures, dystocia will occur in some animals. However, the most effective means of preventing dystocia losses is to manage animals to decrease occurrence.
Breeding/Genetics - The sire, as well as the dam, contributes to the size of the calf. Some dystocias are caused by too large of a calf in a small cow or especially in a heifer. Always be sure to breed your heifers to sires that are proven not to produce high birth weight calves. However, you may not want to go to the other extreme and select sires that produce very low birth weight calves either; small calves tend to grow into small heifers.
Nutrition - The cows/heifers should be supplied with enough calories to maintain body condition and fetal growth. The cows should not be under conditioned or over conditioned. Over conditioning may lead to calving disorders and metabolic problems, whereas under conditioning can lead to decreased production and reproductive performance. Over conditioned cows/heifers can accumulate fat around the pelvis causing a smaller birth canal. You should have a target body condition score of 3.25-3.5. You also want to be sure to maintain a normal calcium balance in the cows. This may be accomplished by feeding anionic salts and extra calcium prior to calving. If calcium levels drop you may have calving problems related to milk fever. If you are experiencing high rates of dystocia you may want to reevaluate your nutrition plan for your heifers and dry cows.
Observation of the cows/heifers close to calving - early intervention can help prevent some of the more difficult dystocias and calf deaths.
Educating your personnel - Knowing when to intervene and what to do is extremely important in decreasing the occurrence of more difficult dystocias and calf death losses
Dystocia in Heifers vs. Cows
- The different causes of dystocia in the cow versus the heifer is due to the differences between the two animals. A heifer is still growing, so she will be smaller than a mature cow. Also a heifer has never had a calf before, so the tissues of the birth canal (cervix, vagina, and vulva) have not ever been dilated. Thus, dystocia in heifers is often due to the birth canal not dilating or stretching sufficiently. These dystocias can often be relieved by manually dilating the vagina and vulva.
When dystocia occurs in cows however, it is usually the result of a more serious problem. The size of their birth canal is less restrictive than that of a heifer so when dystocia occurs there may commonly be another disease process going on (i.e. Milk Fever), the calf is extremely large, or the calf is malformed or malpositioned. For these reasons even mild dystocia in a cow may increase the likelihood of a stillbirth and live calves may be more significantly compromised than those born to a heifer with dystocia.
Effects of Dystocia
Any dystocia will have some impact on the calf and dam but that impact typically becomes worse the more difficult the calving.
Increased calf death losses due to increased trauma, increased disease, or inability to adapt to life outside of the dam.
Increased dam death loss and culling rates due to trauma, decreased production, or decreased reproductive efficiency. Cows that experience dystocia have increased stress and are more prone to injury.
Increased number of days opens (decreased fertility).
Decreased milk yield (especially in the first 30 days in milk).
Decreased milk fat.
Increased likelihood of future calving problems
Economic losses due to:
- Calf losses
- Treatment costs
- Increased disease in the herd
- Loss in reproductive performance
Due to year round calving on most dairies, it is important to keep good records to monitor the incidence of dystocia in order to determine if there is a problem.
Interesting Facts About Dystocia
As calving difficulty increases, the percent of cow and calf deaths increases.
Bull calves are usually more compromised than heifer calves because bull calves are usually larger.
Some studies have shown that there is an increased
incidence of dystocia in the winter verses the summer This may be due to decreased exercise in the winter.
Dystocia is the major cause of stillbirth.
Approximately half of the calf losses from birth to weaning occur in the first day of life
Dystocia Scoring System
Dystocia is usually put into categories according to difficulty. This is helpful in record keeping and in the communication between personnel.
An example of a record keeping dystocia scoring system
no assistance required
1 - easy pull - typically means a single person pulling
2 - hard pull - typically means 2 people pulling
3 - mechanical pull (calf jack used)
4 - c-section
An alternative example:
1 - no assistance required
2 - easy pull
3 - hard pull, mechanical pull, or veterinary procedure required
It is important that you develop a scoring system that works for your operation. You may want to include information about whether the calf was malpositioned, whether the calf was alive or dead at the time of assistance, etc.… The system should be simple enough for everyone to understand
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