Understanding pig behavior is valuable for animal management

For people managing and caring for pigs, understanding animal behavior can provide insight into their health, welfare, and comfort in their surroundings. This knowledge can be applied to improve animal handling, fertility, and productivity.

Pigs are intelligent animals and use their senses of sight, sound, smell, and touch to explore their environment. They have panoramic vison spanning 310 degrees with a blind spot directly behind them. To move pigs effectively, people should remain within their field of vision, because if they sense someone in their blind spot, they become anxious, stop frequently, and continue to look backwards. Pigs can see some colors but are not able to distinguish objects at distances that clearly. They often hesitate when they perceive objects and shadows in their pathway, and for this reason, keeping alleyways clear and with good illumination aids their movement. Pigs also have a strong sense of smell and use their snout to explore and receive signals by pheromones. They can also hear in the low and high frequency ranges.

Pigs are notoriously heat-intolerant and lack sweat glands over most of their body and that is why modern pig management prioritizes methods to help keep pigs cool in summer. In the wild, pigs wallow in mud to cover their skin to minimize the effects of the sun.

Pig owners and caretakers routinely walk their barns daily to observe their animals. It is important to recognize behavioral signals that provide clues to their welfare, such as their location in their pen or stall, body posture, and activity. Under normal conditions, one might expect most pigs to be sleeping, eating, or moving about. However, this can become complicated as these behaviors often depend upon the age of the animals and stage of production, the type of facility, feeding method, and whether animals are individually or group housed.

On a pig breeding farm, a proportion of the animals will be in farrowing, some in breeding, and the majority in gestation. Sows in farrowing are housed in crates that protect pigs from being crushed when the female lies down. But in the days and hours before farrowing, sows spend more time changing from the standing to the lying position. But once the pigs are born, both sows and pigs spend the majority of their time in the lying position, sleeping and nursing. The sow requires a cooler environment when nursing but the newborn pigs with limited body fat seek warmth from other pigs, the sow, or heat lamps or mats.

Watching where and how the pigs are lying can provide clues to their thermal comfort. In breeding and gestation, sows spend the majority of their time resting while periodically getting up to eat and drink and to interact with others when they choose. In stalls or in pens, pigs can also indicate whether they are hot or cold. Animals that are cold limit body contact with lower temperature floors, and may stand more and try to make body contact with neighboring pigs. Pigs that are hot show opposite behaviors, and maximize body contact with the floor, limit body contact with other pigs, stand less often, and drink much more frequently.

Feeding time is a critical period to assess pigs, and if the herd is fed once each day, all sows are expected to be up and excited. Looking for animals that are not up and eating suggests illness or injury. Even for sows that are up, it is important to see animals with poor body condition, drooping head and tail, lameness, and abnormalities such as cuts, abrasions, swellings, and discharges from the eyes, nose, or rear.

In group housed animals, pigs establish social hierarchy and these interactions can impact all or a sub-population of the animals and disrupt feeding, sleeping, and health. Intervention can include adding distractions, changing the layout or feeding times, and removing the bully or the submissive sow.

When walking a barn, listening can also provide important clues especially when the barn is calm and quiet. Caretakers should be attuned for the sounds of animal distress including coughing, sneezing, and squealing, as well as to the sounds of the barn that include running water, feed systems, fans, heaters, and metal banging. It is also possible to gain a new perspective when walking a barn at odd times of the day and night. Big and small barns each have microenvironments and sensing those changes, especially in the most stressful times such as the hottest part of the day in summer, and the coldest periods at night in winter, can provide insights into what the individual animals are experiencing.

As animal caretakers we have the capacity to assess the animals and their barn, and make adjustments to try and improve air temperature and quality, clean and dry floors, feed and water access, and animal health and safety.

Rob Knox is a swine Extension specialist, Department of Animal Sciences, University of Illinois.