Predicting Calving Time: What are Your Options?

Accurate recognition of the start of calving is critical to identify if a cow needs assistance to deliver her calf. Regardless of the reason why a cow may need help delivering her calf, this event is known as dystocia, and has numerous negative effects in cow and calf health and performance. Scientists in the field have focused on identifying and accurately measuring physiological and behavioral changes that cows experience around calving in order to develop farm practices and tools capable of effectively predicting calving within hours of its occurrence. Such responses are associated with physiological processes that trigger parturition and cause cows to behave in a particular manner (e.g., decrease lying time, increase tail raising) and cause her tissues and organs to experience visual morphological changes (e.g., relaxed pelvic ligaments, swollen udder).

These changes, known as imminent signs of parturition, can be accurately identified by well-trained maternity personnel. The visual observation of imminent signs of parturition has been shown to accurately predict calving within 12 hours of parturition, with observation of relaxation of pelvic ligaments and teat filling being more accurate signs when monitored every 2 to 3 hours. An alternative for this option is using video cameras in prepartum pens or calving pens. The most effective approach that this technology may be applied is in combination with farm personnel walking prepartum pens. Once personnel identify cows with imminent signs of parturition, cows can be moved to the calving pen, where progress is monitored through a video camera. This option could allow for some multitasking for the office employee while decreasing the exposure to inclement weather for field personnel, which could have a positive impact on personnel attitude and work environment. Although the conventional and standard approach is effective, there are other technological options available that mostly focus on assessing changes in behavioral patterns of cows approaching parturition.

There are several cow behaviors that change within 24 hours before calving and have been identified as calving time predictors; however, the earliest they were shown to predict calving was within 24 hours, with some behaviors showing some potential for predicting calving within 4 to 6 hours. Some of these behaviors are lying time (decreases 24 hours before calving and increases 2 hours before calving), restlessness (increases 24 hours before calving), insolation (increases the day of calving), rumination time (decreases 4 to 6 hours before calving), and tail raising (increases 2 to 4 hours before calving).

A question that always remained was if cows that will experience dystocia express different behavioral patterns compared with cows that will experience normal calvings, and if those changes could be used to predict calving difficulty. Numerous scientific studies have researched this theory without finding any significant differences in behaviors such as lying time or restlessness, or at least not changes that could be easily identified by farm personnel or available calving monitoring technologies. However, some small studies reported that dystocic cows had more lying bouts (transition from lying to standing position) and decreased feeding time 24 hours before calving, which reflects the potential for developing new tools to accurately monitor these subtle changes in order to predict, and therefore properly assist, difficult calvings.

Most of the scientific studies that have found these associations used accelerometers (activity monitors) or video cameras that do not provide a calving alert system or data summary, which have very low field applicability due to the time-consuming data processing involved. Now there are commercially available tools that measure some of the behaviors mentioned above to predict calving time. These options could be grouped into four categories:

1. Activity monitors
2. Muscle contraction monitors
3. Intra-vaginal thermometers
4. Calf expulsion detectors

The first group includes devices that measure specific cow behaviors such as tail raising (e.g., Moocall® Sensor; Moocall Ltd., Irish Farm Centre, Dublin, Ireland). The second and third groups measure more subtle changes such as abdominal contractions (abdominal belts) and changes in temperature in the vaginal cavity (e.g., Vel'Phone, Medria, Châteaugiron, France), while the fourth group are devices that are placed inside the vaginal cavity and send a signal once they drop to the ground due to the fetus moving forward in the birth canal.

All these devices are programmed to send a radio wave signal, once the specific behavior or process is identified, to a data processor, which interprets the data and sends an alert (voice message or text) to the producer's phone. Although these devices were developed based on known physiological changes in cows around parturition, there is still a lack of scientific data backing up the accuracy of these devices at predicting calving time. There are some scientific studies that suggest that calving prediction activity tools (Moocall® sensors) may be fairly accurate at predicting calving within 2 hours of parturition and that intra-vaginal temperature and calf expulsion monitors (Vel'Phone® sensors) may decrease unnecessary calving assistance (dystocia score 2 [cow assisted by one person without using obstetrical chains or ropes]), and in turn, may decrease stillbirths, retained placentas, and metritis. However, further larger research studies are needed in order to properly assess field accuracy of these devices. Furthermore, other factors such as cost of implementation and device maintenance must be considered as well when thinking about implementing these technologies.

Accurately identifying calving time is critical to properly assist dystocic births in a timely manner and decrease the negative effects of dystocia. As mentioned in previous articles, having trained personnel and well-developed protocols are effective methods; however, there are other, more technological, options for predicting calving time that could be added to the farmer's toolbox. Although these technologies have promising features, there is still a lack of significant scientific data backing them up. To date, having well-trained, reliable maternity personnel and well-developed calving monitoring and assistance protocols may be the best available option to manage your maternity area.

Originally published in Lancaster Farming