A research scientist with the Prairie Swine Center says the size of the group can effect the level of aggression demonstrated by gestating sows.
On behalf of Swine Innovation Porc, in response to requirements for pork producers to move to loose housing of sows by 2024, scientists have been examining the social interactions of group housed sows.
Dr. Jennifer Brown, a Research Scientist Ethology with the Prairie Swine Centre, acknowledges there is debate on the best group size.
Clip-Dr. Jennifer Brown-Prairie Swine Centre:
Smaller groups of sows, if the sows are familiar and they've been managed in the same group, so familiarity is a big part of it and if sows are mixed with sows that they were previously exposed to, there will be minimum aggression.
If you have a moderately sized group, a little bit bigger group, then you might see a more aggression so it's important that sows have a flight distance, so a pen area where they can get away from a sow that's being aggressive towards them.
Again, it's still somewhat debated because when you get the very large group sizes we see much less aggression.
Harold Gonyou at the Prairie Swine Centre did some research on this using finisher pigs and they found that animals that are reared in a very large group adopt a much more passive attitude toward the other members of their group.
There is some theories about this because, if you're in a very large social group, it's really not worth your while to demonstrate that you're dominant over every other individual.
It becomes more and more work to do that.
Pigs, and you could say humans as well in a city versus a country, in a city you don't need to demonstrate who you are to every person you meet.
Source : farmscape