The 2014 National Animal Health Monitoring System (NAHMS) dairy report shows that on average, 5.6 percent of all full-term pregnancies terminate in a dead calf. Dead on arrival (DOA) or stillborn calves are defined as being full-term but not surviving beyond 48 hours after birth. This average indicates there is a lot of room for improvement in the dairy industry.
The value of heifer and bull calves fluctuates with the market. So one might think that when markets are low, DOA calves are no big deal. When markets are high, however, it becomes a major concern because of calf value. The fallacy of this thinking is that a stillbirth or DOA calf has a much greater impact on the cow.
A Cornell study several years ago reported cows that experience stillbirths are at higher risks of culling and death. Average days open also increased by 88 days compared to cows that had live calves.
The value of heifer calves is very important, not only for their intrinsic market value, but also as replacements to maintain and increase herd size through internal growth. Figure 1 illustrates the projected growth of a herd comparing a 2 percent DOA rate to a 10 percent DOA rate given all other parameters stay the same for the 10-year time period.
By the end of 10 years, the herd with a 2 percent DOA rate would have an additional 592 calves born in the 10th year to either sell or continue growth of the herd.
Records showing an elevated DOA rate are an opportunity to review the dairy’s data and evaluate risk factors for DOAs. Once those risk factors are identified, appropriate interventions can be implemented. First, assess if the data is real. Too often, the data is altered in fear of negative consequences from management as a result of losing a heifer calf.
In this instance, the sex is changed to male in the records. The number of DOA male calves is a well-documented risk factor.
Other risk factors include:
- Lactation number – first calving is a much higher risk
- Dystocia/calving ease
- Calving intervention
- Gestation length (greater than 293 days)
- Body condition score
- Size of cow/heifer relative to size of calf
- Twins
Many dairies practice “just in time” maternity management to better utilize resources. This requires a much higher level of supervision and better observational skills. The staff must be able to properly identify cows when calving is imminent and move them to a calving pen.
The risk of not-frequent-enough observation or skilled observation can cause cows to either calve in the wrong pen or be moved into a calving pen in the middle of the calving process (Stage 2 of parturition). Once a cow is into Stage 2 of parturition (feet showing), any disruption will stop the process, and it will take a little while to get started again.
This presents a larger risk when the observing staff notices calving has stopped and intervenes when it is not needed or are in a hurry because of other competing responsibilities.
The process of a normal birth is important to the survival of the calf. When birth occurs, the calf transitions from a total fluid environment within the cow to a total air environment where the calf must breathe, eat and heat itself. In this process, the lungs must be cleared of fluid, the umbilical cord is severed and the calf enters a colder atmosphere. When we speed this process up, the transition is negatively impacted.
As a quick review, there are three stages to calving or parturition. The first stage is dilation of the cervix and usually goes completely unobserved. The sensitivity of the uterus changes, as well as the rate and strength of contractions.
Some noticeable behavior changes include isolation (if possible), discomfort or nesting behavior. Toward the end of Stage 1 and beginning of Stage 2, more behavioral changes occur that are easily detected, such as an elevated tail, increased tail switching and mucus discharge.
Stage 2 is the actual delivery of the calf. It begins with fetal membranes entering the birth canal and ends when the calf is born. The entrance of fetal membranes stimulates final dilation of the cervix if not already complete. The calf appears in the birth canal with the front feet leading and the head quick to follow.
When the calf enters the birth canal, uterine contractions are stimulated to complete the delivery of the calf. The Stage 2 process is not long, and in mature cows, normally lasts about 30 minutes. For first-calf heifers, it can last about an hour.
Stage 3 of calving is the expulsion of fetal membranes. This will occur within eight to 12 hours after the calf is born.
There are several technologies on the market to provide alerts to managers and staff that calving is eminent. They each use different technologies to record and transmit behavior or physiological changes at calving. Each has its own advantages and disadvantages in providing clues to help “just in time” calving management. 
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Andrew L. Skidmore
- Zalliant LLC
- Email Andrew L. Skidmore
- JMB North America
