26 March 1999

Early mixing is time for most sow fighting

MOST fighting between unfamiliar sows takes place in the first few hours after they are mixed at the post-weaning stage, according to ADAS Terrington researchers.

Speaking at this weeks British Society of Animal Science conference, Roger Kay said where space available in a mixing arena provides a potential flight distance of 14m (45ft) or more, a defending sow has the chance to retreat from 95% of aggressive encounters.

But while a generous space allowance may be sufficient to allow subordinate sows to avoid trouble on the first day after mixing, skin damage injuries still occurred as a result of fights, said Mr Kay. "More work is needed to develop commercial systems, where space is more limited, and in which pecking orders can be established without increasing aggression and skin damage."

His comments are based on a study mixing unfamiliar sows at weaning. This involved measuring flight and chase distances, incidence of aggression and levels of skin damage occurring when newly weaned sows were mixed in a large arena where flight and chase distances were unlikely to be limiting factors.

Eight groups of six unfamiliar sows were mixed in an 18m x 10.5m (59ft x 34ft) arena at weaning. They were removed on the second day for individual stall feeding then returned to the arena with all aggressive encounters recorded.

Of all the interactions 76% were brief, 16% were one-sided fights and 8% two-sided fights with the type of interaction having a significant effect on flight and chase distances, said Mr Kay.

For all types of interaction 50% of flight distances were under 4.7m (15ft), 95% under 13.6m (44ft) and 4% over 20m (65ft). In 63% of all interaction there was no chase by the attacker and in 95% of all attacks, chase distances were under 6.8m (22ft).