1. Cull aggressive sows or put them back into individual sow stalls.

2. Small groups of 5 to 6 sows will work well if the sows are never mixed after their initial grouping. Large groups are recommended when sows are constantly being mixed. Large groups of pigs fight less than small groups, when pigs are mixed; 80 sows or more per group.

3. In bedded systems 50 to 60 sows per electronic feeder. In a totally slatted system more feeders may be required to reduce fighting around the feeder. On slatted floors, stock at 45 sows per feeder. Never put all the sows on a single feeder. Equipment companies will often over estimate the number of sows that can be put on one feeder.

4. Spread feeding stations out around the room to prevent fighting.

5. When electronic feeders are used there must be a period when the feeders are shut off. This will promote rest. Turn the feeder back on when the sows are resting. Overloading a single feed station is one of the most common causes of system failure.

6. Keeping sows the first four weeks in individual stalls will increase conception rates. This is most important for new gilts. In a well managed system this time can be reduced.

7. In totally slatted systems, provide some straw for eating and rooting. Other roughages could be used. We need to figure out a way to feed straw or other roughage and prevent it from going through the slats. Feeding roughage will also help reduce fights.

8. Start a group housing system with new gilts.

9. Non slip flooring is essential to prevent leg injuries.

10. Lots of little details are important. A lack of attention to details can cause failure.

11. In systems that do not use electronic feeders, the sows should be sorted by eating speed to reduce fighting. Some pigs are fast eaters and some are slow eaters.

12. There are genetic differences in how much pigs fight and tail bite. Some genetic lines fight more than others. Within a genetic line, there will be high aggression and low aggression sows. For all the years that sows have been in individual sow stalls, there has been no selection pressure for less aggression. Don Butler at Smithfield Foods reports that they changed sow genetics to reduce fighting.

13. Group housing conversions should be started in buildings where the unit manager is enthusiastic and wants to make it work. A negative manager will cause system failure.

14. In systems that use lock up stalls for feeding, sow housing pens must have wide gates to prevent injuries when sows rush out of the pens to the feeding stalls.

15. Sows will fight less in systems that have straw or other bedding. A system with straw bedding provides excellent welfare but in some parts of the world the use of straw bedding is not practical.

16. Experiment with the timing of feed delivery and gate opening to prevent sows from rushing towards the feeders.

17. Successful group housing requires a higher level of stockmanship skills than individual sow stalls. A patient, good stock person is required to train gilts to use electronic sow feeders.

18. When feeding stalls are used in conjunction with a straw bedding lying area, a wall must separate the two areas to prevent dunging in the sleeping area. Openings in the wall must be 300 cm (10 ft) wide. This is wide enough for hungry sows to pass through to the feeding stalls without injuring themselves but narrow enough so that the sows will perceive the sleeping area as a separate place.

19. Group housed sows are most likely to bite and injure each other shortly before farrowing. If injuries are a problem, remove sows from the group one week before farrowing. In the wild, sows will isolate themselves before farrowing.

20. Do not mix sows during the first four weeks after breeding. Fighting may interfere with implantation of the embryo and reduce litter size.

21. When sows are mixed, fighting will be reduced if all the animals are put in a new pen. This prevents the problem of the new sows invading the home territory of the sows that are already in a pen.

22. Build a long exit lane from each electronic feeder. This prevents a swo from immediately returning to the entrance gate of the feeder.

23. Big groups may work better than smaller groups. Dr. Larry Coleman, a veterinarian in Nebraska, puts groups of 150 to 300 sows on multiple electronic feeders. This has worked well for them on totally slatted floors.

24. Animals housed in large groups will form their own societies within the building. To facilitate formation of social groups, the building is partitioned into a series of 10ft (3m) to 12ft (3.5m) alcoves, along each exterior wall. In the center there is an 8ft (2.5m) alley. A wide alley is essential so animals who do not like each other can pass without getting too close.

25. Remove alleys for people from group housing systems. This will help create tame, calm sows that will not be afraid of people. When people are in their pens all the time, the sows will become so tame that ultrasound pregnancy checks can be done by walking up to the sow.

26. Pen sows in group housing by parity. Never mix gilts with older sows.

The ideas and tips came from both presentations and discussions at the 2003 and 2015 Swine Seminar in Banff, Alberta, Canada and the 2003 American Society of Animal Science Meetings.

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