Farmed Pig: Aggression Management at Mixing

Aggression when unfamiliar pigs are mixed causes injuries, stress, and welfare suffering that is predictable and partially manageable through appropriate mixing protocols.

Key Facts

Pig aggression at mixing peaks in the first 24-48 hours and typically resolves within 3 days
Injuries from mixing aggression include ear tears, skin lacerations, and occasionally serious eye or joint damage
Larger pen spaces that allow avoidance reduce the severity of mixing aggression
Mixing at night when pigs are less active reduces but does not eliminate aggressive encounters
Providing substrates that distract pigs after mixing reduces aggression by providing alternatives to fighting
Pheromone products including Suprelorin and synthetic versions of maternal pheromones reduce aggression

Welfare Considerations

Pig mixing aggression is one of the most predictable sources of welfare suffering in intensive production - anticipated, routine, and yet managed more by acceptance than prevention. The injuries sustained in mixing fights cause acute pain and chronic wound management challenges. Systems that maintain stable social groups from weaning through slaughter, while more logistically demanding, virtually eliminate mixing aggression. Where mixing is unavoidable, protocols that minimise its severity - adequate space, distraction enrichment, timing, and pheromone products - should be mandatory welfare requirements rather than optional additions.

What You Can Do

Support welfare standards requiring mixing management protocols in commercial pig operations
Advocate for stable social group maintenance as a welfare standard from weaning to slaughter
Choose pork from systems demonstrating investment in mixing aggression reduction
Support research into practical mixing management strategies for commercial pig production
Donate to welfare organisations developing and disseminating pig mixing management guidance