John Anastasiou, j.anastasiou@nuevo-group.com
Aggression in group-housed sows is one of the most common welfare and production challenges in modern pig farming. Fighting increases the risk of injuries, lameness, abortions, culling and reduced reproductive performance. While aggression is often viewed simply as a behavioral issue, it is, in reality, the outcome of several interacting factors.
Aggressive behaviour in pigs is not necessarily the problem itself; it can be a sign that the animals are struggling to cope with their environment. Factors such as overcrowding, competition for feed or water, mixing unfamiliar pigs, inadequate enrichment, discomfort, or other sources of stress can increase aggressive interactions. Addressing aggression is most effective when the underlying environmental and management factors are identified and improved, rather than focusing solely on the aggressive behaviour itself.
Housing and Management
Housing remains one of the major drivers of aggression. Limited floor space, poor pen design, competition at feeding stations, inadequate access to water, slippery floors, heat stress and poor ventilation all increase social tension within a group.
Management practices are equally important. Mixing unfamiliar sows, frequent regrouping, large group sizes and poor body weight uniformity all increase competition while social hierarchy is being established. Most aggressive interactions occur during the first 24–72 hours after mixing.
Health Status
Pain and disease significantly increase aggressive behavior. Lameness, hoof disorders, shoulder ulcers, urinary tract infections, mastitis and chronic inflammatory conditions reduce the sow’s tolerance to stress and make normal social interactions more confrontational. Healthy animals are simply better able to adapt to social challenges.
Nutrition – An opportunity often overlooked?
Although nutrition has traditionally focused on satiety through fiber inclusion, our understanding has evolved considerably over the last decade. Today, nutrition is recognized as one of the key tools for improving resilience – the animal’s ability to cope with daily physiological, environmental and social challenges.
Chronic stress continuously activates the immune system, increasing oxidative stress and maintaining a state of low-grade inflammation. Under these conditions, nutrients are diverted away from production and reproduction towards maintaining homeostasis. The consequence is not only reduced performance but also altered behavior. Animals under continuous inflammatory pressure become more reactive, less tolerant and more likely to engage in aggressive interactions.
Recent research (Carabotti et al., 2015; Jian et al., 2025; Woś et al., 2025) on the gut – immune – brain axis has reinforced this concept. Gut health, oxidative stress and inflammation are closely connected with stress responsiveness and behavioral stability. Rather than viewing aggression purely as a behavioral issue, it should increasingly be considered a consequence of reduced physiological resilience.
This is where modern nutritional strategies can make a meaningful difference. Beyond simply meeting nutritional requirements, functional feed additive solutions that help reduce oxidative stress, modulate inflammatory responses and support gut integrity may enhance an animal’s ability to respond effectively to everyday challenges.
At nuevo, this philosophy has guided the development of nuphoria. Rather than targeting aggression directly, nuphoria is designed to improve the animal’s resilience by supporting its natural ability to control inflammation, manage oxidative stress and maintain intestinal integrity. As animals become physiologically more resilient, they are better equipped to cope with environmental and social stressors, resulting not only in improved welfare but also in better health, productivity and reproductive performance.
Looking beyond behavior
Perhaps the questions we should ask is not “Why are these sows fighting?” but rather “Why are these sows less capable of coping with the challenges around them?”
This shift in perspective encourages us to look beyond aggression as an isolated behavioural problem and consider it within the broader context of the animal’s physiological state and capacity to cope with stress.
Aggressive behaviour may therefore serve as an early indication that an animal is struggling to adapt to environmental, social, or physiological challenges. Supporting resilience, rather than focusing solely on reducing aggression, may represent a more holistic and sustainable approach to modern sow production.
Ethical nutrition: Supporting the animal, not just the production!
At nuevo, we believe that sustainable productivity begins with healthy, resilient animals. Rather than focusing solely on maximizing performance, our approach to ethical nutrition is based on supporting the animal’s natural physiology – helping it cope more effectively with stress, maintain immune response and preserve gut health.
When nutrition is used to improve resilience rather than simply correcting production losses, better welfare and improved performance become complementary outcomes rather than competing objectives. This philosophy drives the development of our nutritional solutions and reflects our commitment to producing more efficiently, more responsibly and with greater respect for the animals in our care.
Sources:
https://pmc.ncbi.nlm.nih.gov/articles/PMC4367209