Sow exercise benefits found lacking

Researchers wanted to know if a middle ground solution between stalls and open housing was a reasonable option

Pregnant sows have an intrinsic desire to leave their stalls, say swine health experts at the University of Saskatchewan.

But giving sows periodic freedom to exit the stall and move about the barn doesn’t significantly improve the lives or welfare of the animals.

“We were able to conclude that there is a level of motivation for the sows to have that freedom of movement … (even) when they were adequately fed,” said Yolande Seddon, an assistant professor at the Western College of Veterinary Medicine who studies swine behaviour and welfare.

“(However) if you’re going to exercise sows at a low level, once per week, the welfare benefits were (small).”

For the last couple of years, Seddon and her U of S colleagues have been studying the idea of letting gestating sows out of stalls as a way to enhance their quality of life. Most sows in Canada are kept in stalls, or gestation crates, because pregnant sows can be aggressive and it’s more complicated to manage sows in loose housing.

The hog industry is moving toward group housing of sows so that the animals can express natural behaviours and have greater freedom of movement. According to the code of practice for raising pigs, all sows were supposed to be in group housing by the end of 2024. This summer, the National Farm Animal Care Council put forward recommendations that the date be pushed to 2029 because the 2024 deadline isn’t considered feasible.

“If you rush this transition, if you do it poorly, that can actually have a negative impact on animal behaviour and animal welfare,” said Hans Kristensen, a pork producer from New Brunswick.

“This is more about taking the time to do it and do it right. The industry is 100 percent committed to this transition. We just want to get it right.”

Seddon and her team wanted to know if a middle ground solution between stalls and open housing was a reasonable option.

If sows kept in stalls were given periodic freedom, would that enhance the quality of their life?

Before answering that query, Seddon needed to study a different question: do pregnant sows actually want to leave their stalls?

The researchers set up a system where sows kept in stalls could press two buttons. By repeatedly pressing a button with their snout, the sows could either get more food or get out of the gestation crate. The animals pressed the “food” button more often than the “freedom” button, suggesting that additional food was more important.

However, when the scientists gave the sows more feed, the animals continued pressing the freedom button.

“Even when you’re satiated, there is still motivation (to exit),” Seddon said. “We interpreted that there is an intrinsic motivation to have freedom of movement… We did look at them when out of the stall … and predominantly (they) would be searching for food, but they (spent) equal time nosing (other) sows through the bars and walking around.”

Having determined the sows do want to roam about, the scientists devised a different test to see if they benefitted from periodic exercise.

They set up three scenarios:

  • Sows kept in stalls all the time.
  • Sows kept in group housing.
  • Sows kept in stalls and exercised once a week for 10 minutes, walking in the alleys of the barn.

Seddon and her team selected 10 minutes once a week because a producer might be able to provide that level of activity.

“We thought (it) might be reasonable, but in reality, with some large sow herds, it might be even (less) than that,” she said, explaining some barns house hundreds of sows.

It would probably require a full-time employee to move the animals in and out of their stalls.

“(But) if we (could) see a benefit from 10 minutes, once a week, it tells us something,” she said.

To measure welfare benefits and productivity, the scientists tested hair samples for cortisol (a hormone associated with stress), counted the number of piglets born live, monitored things like sitting, standing and lying and tracked other behaviour that might indicate better welfare.

In the end, group housing and periodic exercise did seem to help older sows.

“Providing stall-housed gestating sows with 10 minutes of exercise once per week benefitted only the performance of older… sows. However, we did not see measurable benefits from exercise in younger sows, whom tend to be in better physiological condition,” the researchers wrote in a paper published on the Prairie Swine Centre website.

“Old … sows that were group-housed or stall-housed with weekly exercise had a greater number of live born piglets compared to sows housed in stalls throughout gestation.”

The scientists also studied the economics of periodic exercise.

They found it doesn’t make financial sense.

Assuming a sow herd of 1,200 animals, the cost of moving pregnant sows in and out of their stalls would add up to $127,400 per year in additional labour costs. That’s assuming a producer could recruit workers willing to do such a job.

Given the marginal welfare benefits and slight improvement in productivity, a program of periodic freedom doesn’t make sense.

“This is probably not the most valuable approach, considering the amount of effort it would require,” Seddon said.

“It doesn’t really compare to group housing…. The group housing gives them constant freedom of choice in their environment.”

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