Meristem: Pork Science

Group sow housing could benefit the swine industry over the long term by improving production practices, say Alberta Agriculture, Food and Rural Development (AAFRD) specialists.

However, there is a reason why producers moved away from group sow housing in the first place, says Kelly Lund, Engineer-in-Training for AAFRD; it wasn't seen as offering the same efficiency as individual gestation stalls. "The challenge lies in merging the economic benefits of individual stalls with the animal welfare benefits of group sow housing while minimizing that system's unique drawbacks," says Lund.

AAFRD hopes to develop best management practices for group sow housing by incorporating results from a new three-year study that examines the effects of the system on animal health, behaviour and, perhaps most importantly, productivity. Lund, who is on the research team, says the research will add to the expanding body of work in the field of sustainable swine management practices.

The research compares three different sow-housing systems and a gestation stall system. Each with a different feeding strategy, one includes free access stalls in which the animals can access a protected feed stall at their choosing. Another features a dual-level mezzanine system with feed stalls that provide no protection at feeding but provide a slightly larger floor area thanks to a second-floor mezzanine. Another incorporates an electronic sow feeder where sows are protected at feeding but can only be fed one at a time.

In one facility, all groups will be subjected to dynamic grouping, where animals are added and removed on several occasions. Static grouping will be used at the second facility.

Animal health, behaviour and productivity are interrelated, says Lund, and researchers have to select from many indicators that could be used to assess animal welfare on a quantitative and qualitative basis. Scratches, lameness, aggression and culling decisions are key measurements for this study.

In terms of behaviour, the research team has chosen to focus on aggression in the initial mixing of the groups as it is the behaviour that can have the most impact on health and productivity. Scratch scoring is one of the methods used to gather information on herd aggression upon the introduction of new animals, as well as correlation with video observation and automatic tracking software.

Initial scratch scoring observation indicates a decreasing level of aggression over time. "Not surprisingly, there's a lot higher number of scratches in the initial mixing over the first couple of weeks but the number actually decreases over gestation," says Lund.

Measurements of lameness are done on a one-to-five scale and essentially measure the locomotive ability of the sow. Lameness and longevity, how long a breeding sow is kept in the herd, are highly connected, says Lund, and present a productivity challenge.

"The swine industry has a high culling rate of 35 to 40 per cent per year and, second only to culling due to reproductive problems, is culling due to lameness," she says. "I know of some economic analysis that says the break even point on a new sow is after her third or fourth litter. The fact is, many producers don't hold their sows much longer than fifth parity. They've just started to recover the cost of the animal and they're culled, quite often for lameness or health issues. Increasing the longevity of a sow can have a significant impact on the bottom line of a farrowing operation."

Reproductive performance is also measured, but Lund says they are not expecting to find much difference. "Many research studies have shown there's not a major difference in reproduction between group houses and gestation stalls in favour of either system. Any major difference has more to do with management. But it is important data for the industry."

Lund says it's too early in the research process to make any science-based recommendations to hog producers, but there are a few things they should know based on initial observation. She recommends that producers starting an enterprise or on the verge of major renovations seriously consider a group housing system, if for no other reason than it is the direction the industry and the market opportunities are headed.

Secondly, Lund recommends static breeding groups over dynamic ones if facilities permit, simply because hogs tend to display less aggression when they're in consistent groupings. Free access stalls have also appeared to lessen overall herd aggression as the animals have the ability to get away from the herd's more aggressive members.

"While we are aware of many well-functioning group systems, both static and dynamic, our initial recommendation would be to look at a barn design, number of rooms and number of feed stalls that would allow static group management."

The AgTech Centre is part of Alberta Agriculture, Food and Rural Development's Technical Services Division and has a mandate to support all aspects of agricultural sustainability. Organizations funding this research include Alberta Livestock Industry Development Fund (ALIDF), Alberta Agricultural Research Institute (AARI), Alberta Farm Animal Care (AFAC), Alberta Pork, Agriculture and Agri-Food Canada, AAFRD and the University of Alberta. Collaborators include Prairie Swine Centre and Hypor Genetics.

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