Physiological and behavioral indicators of stress in pigs

The intensive development of pig farming can cause stress in pigs, which negatively affects their welfare and productivity. The most common sources of stress are changes in the conditions of keeping and feeding technology, socialization, and microclimate parameters. In order to monitor the response to stress, you can use indicators that are based on stress coping mechanisms in pigs. These indicators help make decisions to support animal welfare and productivity. In this regard, the aim of our study was to get acquainted with modern approaches to the use of physiological and behavioral indicators for the diagnosis of stress conditions in pigs. Sows in confined environments have poor welfare and often exhibit stereotyped behavior, and housing animals in group stalls can lead to increased aggression during mixing and feeding, leading to chronic stress. Long-term activation of the stress response, enhanced by the level of cortisol, can affect the reproductive function of animals. A frequently used indicator of social stress is aggressive behavior. It was also established that social stress negatively affects the foraging behavior of pigs. In particular, it reduces the level of consumption and satisfaction from taking feed. Periodic separation from the sow leads to anxiety and changes in the behavior of piglets, negatively affects the condition of the digestive tract and body weight of weaned piglets. Limiting night feeding of piglets disrupts not only the rhythms of their behavior, but also changes the composition of the intestinal microbiota, lowers the serum levels of hormones associated with depression and anxiety. Stress is a complex problem that affects all the main systems of the pig body, causing changes in the physiological state, behavior and performance of the animals. The main signs of behavioral change are aggression, reduced feed intake, changes in body position, posture, mobility, increased vocalization, and apathy. Among the physiological signs, this is primarily an increase in body temperature, rapid breathing and heartbeat, as well as hormonal changes, a decrease in immunity, a decrease in body weight gain, and a violation of the reproductive function of sows. Thus, stress in pigs is accompanied by a complex of changes in behavioral, humoral and neurophysiological factors that can be used to assess the state of stress in this animal species.