Dr. Steve Hendrick, DVM, says one of the most critical steps in reducing disease and loss in newborn calves is reducing dystocia.
Hendrick cited a study that examined the causes of calf mortality, and said the main cause of death in stillborn calves was due to dystocia. Other causes of stillborn calves include thyroid gland lesions, myocardial necrosis or myopathy (dead or dying heart muscle or dysfunctional heart) and skeletal myopathy or necrosis.
Reducing the rate of dystocia, or difficulty calving, can significantly impact calving percentage. “Heifers are at greatest risk for dystocia,” said Hendrick, adding that the dystocia rate in heifers is at least two to three times the rate seen in cows. “We tend to pay more attention to heifers at calving, and the best way to do that is to breed and calve heifers at least two to three weeks earlier than the cowherd. This allows more time for monitoring, and also more time for heifers to recover for breeding.” Hendrick said while the rebreeding time for cows is 60 to 75 days post-calving, for heifers that time can be up to 90 days.
Breeding heifers to low-weight bulls with known EPDs also helps reduce the risk of dystocia. Hendrick said the goal is to seek “curve bender” bulls – those which produce calves with below-average birth weights but after birth, the same calves grow at a normal rate. Pelvimetry, which employs an instrument to determine pelvic measurements, was used years ago but Hendrick said it isn’t a reliable measure of predicting dystocia.
Tracking birth weights can help determine whether the bull selection is appropriate. When practical, Hendrick recommends using a scale to determine birth weights of calves, especially those born to heifers. A simple sling scale can be taken to the field if animals are calving on pasture.
Since heifers carrying bull calves are more likely to experience dystocia, it’s worth spending money on sexed semen. Hendricks said because heifers typically have good conception rates, the investment is worthwhile.
Heifers should calve at 85% of their mature body weight, and should be in good condition. “What’s really important is not to get these animals too fat,” said Hendrick, adding that a body condition score of around 3.5 is ideal. “To affect this, we need to be cognizant about the winter feeding program. I know they’re dry-lotted sometimes, but I like to see heifers get some exercise, especially the kind of activity they get with grazing.”
Depending on herd size and management style, grouping animals can help. “Keep heifers, maybe the first and second calvers, and skinny cows separate to pay more attention and provide more calories,” said Hendrick. “That allows time to put some flesh on and make sure they’re in good condition.”
Hendrick said using camera systems to detect impending calving is a useful tool for producers because animals can be observed without directly disturbing them. However, Hendrick added that even with such technology, frequent in-person checks are important. The goal is to observe but not disturb animals to the point of interfering with the normal labor process. Timid heifers are particularly prone to becoming easily disturbed.
While there’s an advantage to using nighttime cameras with infrared light, it’s important for the safety of both cattle and handlers to have regular lighting if cattle have to be assisted or moved.
Some producers try to influence the time of calving by feeding at a certain time, but Hendrick said there’s only anecdotal evidence to prove that practice is of value. However, Hendrick said it’s worth feeding in the evening for more daytime calvings.
Another important aspect of reducing the risk of dystocia is knowing when to intervene. “If you see a cow that actively strains for 40-45 minutes with no progress, that’s a cow that should be checked,” said Hendrick. “If 90 minutes has passed since the water bag first appeared, you should be checking that animal.”
Understanding the various presentations of the neonate’s hoofs helps reduce the risk of dystocia because someone can intervene before it’s too late. If the hoof surfaces face downward, the calf is likely going to be born in the normal, head-first “diving” presentation. However, if the surfaces of the hooves face upward, the calf may be upside down, but more often backwards, and the animal may require assistance.
If a cow or heifer is in late labor and only the calf’s tail or head is visible, she should be checked frequently and the attendant should prepare for potential delivery problems. Cows that have not yet calved but are observed mothering another calf should also be watched. Any animal, especially first-calf heifers, that appears to be anxious (walking around with tail extended) for more than five or six hours should be closely observed.
If dystocia is suspected, there’s a delicate balance of not interfering too soon and not waiting too long. Those who are attending first-calf heifers should track and time labor events from the moment the animal shows signs of restlessness through water bag appearance and initial presentation. It’s also important for the attendant to determine when an animal requires additional assistance and possibly help from a veterinarian.
Those who assist cattle producers at calving should be aware of normal signs of labor, know when to intervene and know when to request additional assistance. In stage one of labor the calf rotates to the upright position, uterine contractions begin and the cervix dilates. This series of events results in the expulsion of the amniotic sac. The cow or heifer may appear to be unsettled, rise and lie down repeatedly and may begin to strain.
In stage two of labor, the cow will strain frequently and will usually rise and recline in an attempt to ease her discomfort and prepare for delivery. The calf enters the birth canal, and in a normal presentation, the head and feet are visible first, followed by delivery.
Safety is an important aspect of any assistance given at calving. Attendants should be cautious when dealing with timid or frightened animals that may act unpredictably. Attendants should be familiar with proper restraint of animals and have a safe place to work with a laboring animal.
Any animal, even cows with years of calving experience, can have a difficult birth. Watching animals closely as they approach calving dates, understanding what progress looks like and knowing when to ask for help are critical to the safe delivery of a healthy, thriving calf.