As a cow-calf producer, one of your busiest times of year is calving season. It's a high-stakes time, where the results of work and decisions made throughout the year are realized. Bull selection, heifer selection, nutrition planning, vaccination choices -- it all comes down to this: the live calf on the ground.
Seventy percent of the beef calves that die between birth and weaning either are born dead or die within 24 hours of birth. The most common cause of these deaths is calving difficulty, with studies documenting 60 percent to 70 percent of these calf losses being due to difficult births. Additionally, calves born after a prolonged delivery are 2.4 time to 6 times more likely to become ill in the immediate postnatal period than calves born without difficulty. It is critical for the life and health of the calf, and the reproductive health of the heifer or cow, that timely and proper intervention occurs to minimize the negative impact of prolonged deliveries.
So what causes a prolonged or difficult calving? In beef cattle, the single most common cause is an oversized fetus relative to the dam's size. This is most often appreciated in heifers, but is seen in mature cows as well. The second most common cause is incorrect positioning of the calf. This may include the head or a leg being turned back, the calf being backwards, or other position which makes passage through the birth canal impossible. Other more rare causes include the presence of twins, anatomic abnormalities of the calf, or a uterine torsion or twist in which the exit from the uterus is blocked by a tight twist. Rapid detection and correction of these abnormalities is necessary in cattle for which normal delivery does not occur.
In order to know how to determine if a cow or heifer needs assistance in delivering her calf, an understanding of the normal calving process is required. The first stage of labor is a preparatory phase in which uterine contractions begin and the fetus moves into position. During this time, the dam may separate herself from the herd or begin to act uncomfortable. For heifers, this stage may last 12 to 48 hours, while in cows, three to eight hours is more typical. The mark of the end of this first stage is the "water bag" breaking. Stage 2 labor is the phase in which the dam moves into full labor, with active abdominal pressing in order to expel the fetus. In heifers, this may last one to four hours or in cows, 30 minutes to one hour. Once the calf is out, the third stage of labor is initiated, during which continued uterine contractions expel the placenta, which takes six to 12 hours.
Cattle are masters at hiding problems. What should be done during each stage of labor to help ensure that problems are identified early? It can be difficult to detect the first stage of labor in some animals, but when a heifer or cow is noted to be standing off from the herd around the anticipated time of calving, she should be moved to an area where she can be monitored closely for evidence of the water bag breaking or active labor. If this preparatory phase is prolonged, it may indicate that labor cannot be initiated normally and the cow or heifer should be evaluated.
Common causes of cattle not entering the second stage include a breech presentation of the calf or a uterine torsion. More commonly, delays in the progression of labor occur during the second phase. As stated above, Stage 2 labor never should last more than four hours and most animals will have their calf delivered within two hours. In general, if the calf is not delivered within two hours after the breaking of the water bag and the onset of active pushing, intervention is indicated. A skilled individual thoroughly should clean the vulva and, with clean hands and arms, perform a vaginal exam to determine whether or not the cervix is fully dilated and the position and relative size of the calf. Only once the position of the calf is correct and the calf is determined to be small enough to be delivered, assistance may be provided by means of manual traction or use of a calf puller. Great care should be used in how chains or straps are placed on the calf's limbs and how much pressure is applied to a calf in the delivery attempt, as severe damage can be done to the calf's limbs or to the cow with the use of excessive force. For those with little experience in successful calf delivery, a veterinarian should be called two hours after the onset of labor for determination of the most appropriate next step.
Once the calf is delivered, the cow should be monitored for passage of the placental membranes. If passage does not occur in 12 hours, the cow should be monitored closely for general attitude and appetite. Failure to pass the membranes can set up a uterine infection that can cause serious illness or reduction in subsequent fertility. If at any time the cow becomes ill or the membranes are retained longer than three days, even in a healthy-acting cow, your veterinarian should be called as infection of the uterus may occur and prevent future reproductive success.
Delaying intervention during calving difficulty can mean loss of the calf and sometimes the cow or heifer. Close and regular monitoring of cows and heifers during the calving season allows for early recognition of problems and provides an opportunity to intervene when the likelihood of success is significantly greater.
Photo by Texas A&M University, College of Veterinary Medicine & Biomedical Sciences
There are many factors that can casue a difficult or prolonged calving. It is important to know when to intervene for the saftey of the calf and cow or heifer.