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Stress measurements using sow hair

Stress measurements using sow hair

Researchers investigated how housing system impacted stress of sows based on parity  

By Jackie Clark
Staff Writer 

Scientists from South Dakota State University and the University of Saskatchewan worked together to evaluate long-term stress in sows in different housing systems by measuring the concentration of cortisol in hair. 

Hair cortisol concentration (HCC) is used as an indicator of stress because cortisol circulating in the bloodstream is deposited in the hair. 

“I’d seen a bunch of research using this technique on different animals and didn’t see a whole lot in pigs,” Talia Everding tells She was the lead on the project, and has just finished her Master of Science at South Dakota State University. 

She learned the technique at the University of Saskatchewan from Dr. Yolande Seddon, and then conducted the experiment back in South Dakota. 

The researchers placed 34 sows in gestation stalls, and 32 sows in group pens with gilts and parity one sows in one pen and multiparous sows in another two pens. They found that gilts and parity one sows had higher stress than higher parity counterparts in stall housing. In group housing, sows experienced similar HCC levels regardless of parity.

“Overall, the stall sows did have higher HCC,” Everding said. “When we parsed it out by parity grouping, we saw that the younger sows, particularly the gilts and parity one sows, had significantly higher HCC than all the other sows regardless of housing system.” 

Within group housing, no statistically significant differences existed in HCC levels between parity groups. 

“We thought that we would see some more stress in the younger sows in group housing as well just because of those new social interactions that they have and some of the fighting that occurs when you first put sows in group housing,”

Everding explained. The researchers were surprised to see that the group housed animals had similar stress across the board. 

Future research using this method could expand on our understanding of how parity impacts long-term stress, and how HCC may relate to other sow health and performance parameters.   

“One of the shortcomings with our study was, for one thing we didn’t have very many animals,” Everding said. “Doing this on a larger scale and getting more animals would be great.”

More sows would allow for increased statistical power to make conclusions. 

“It would also be great to see the hair cortisol in conjunction with other measures,” she added. Researchers could also investigate parameters that measure behaviour, performance, future breeding, longevity.

Research could also study different types of group housing systems, which can vary dramatically from barn to barn, Everding explained.  

“Floor space allowance, presence or absence of enrichment, type of flooring, type of feeding system, all of those would go into completely changing the way the sows are experiencing or not experiencing stress,” she said. “In our study the sows had a lot of space and that’s not realistic when compared to a commercial operation, but it’s what we had and what we worked with.” 

From their results, producers can decide how they may want to make changes on their farm. Consumer demand and policy requirements in both Canada and the U.S. are indicating at an industry trend away from stall housing toward group sow housing. 

“We saw that the young sows seemed to have a harder time adapting to stall housing,” Everding said. “There is evidence that individual housing causes more stress and so in order to benefit the most stressed animals I would say focus on incorporating group housing with your younger animals first.” 

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