Mixing at young ages reduces fighting in unacquainted domestic pigs (2000)

Pitts, A. D., Weary, D. M., Pajor, E. A. et al.

Abstract

We found no significant relationship between age and the likelihood that a pair of piglets would fight during the first 75 min after mixing. However, the duration of the first fight observed increased from 101?38 s at 5 days to 621?278 s at 26 days, mainly because of higher levels of unretaliated harassment and resting during the bouts. Younger pigs also showed 80% fewer injuries from the fighting. The results suggest some potential welfare advantage to allowing litters to mix at younger ages.