Sow Housing Impacts Productivity, Immune Status

The sow gestation environment does influence sow performance, productivity and physiology, according to a preliminary report from the University of Illinois

The sow gestation environment does influence sow performance, productivity and physiology, according to a preliminary report from the University of Illinois.

But more research will be needed to learn which of several alternative accommodations, if any, provide the best sow welfare and improved productivity over the standard gestation stall.

Results from the pilot study showed:

  • Sows kept in a free-access stall/pen have more lesions and greater neutrophil-to-lymphocyte (signs of acute stress) than sows housed in individual stalls.

  • Increasing the width of an individual stall late in gestation can decrease stress levels (based on cortisol response).

  • Sows kept in free-access stalls/pens and adjustable stalls farrow more male piglets than sows kept in standard stalls.

Overall, the type of accommodations for gestating sows can impact well-being.

To study alternative styles of gestation environment, sows at Day 30 of gestation were assigned to a standard crate (CRATE), an adjustable-width crate (FLEX) or free-access stall/pen system (FREE).

On Day 89 of gestation, the width in the FLEX crate was adjusted to achieve a total 1.6 in. of space between the sow lying down and the sides of the crate.

Sow weight, backfat, body condition and lesion scores were recorded throughout gestation. Blood samples were taken to assess the impact of different accommodations on stress hormones and immune status of the sows. Litter performance was also recorded to learn if gestation environment can influence offspring. All measures were used to assess the overall well-being of the sows.

Figure 1 illustrates the lesion severity of all treatment groups throughout gestation. Sows kept in the FREE system had more severe wounds than sows in the other two treatments; however, lesion severity among these sows declined after Day 60 of gestation. Sow body weight and condition score were unchanged by sow environment.

Figure 2 represents a decrease in cortisol after expanding the width of the stall in FLEX-kept sows, indicating that slightly increasing the width of the stall decreases the stress level later in gestation.

Figure 3 depicts sow immune status in all three environments prior to placement in treatment (Day 30) and 24 hours after placement into the treatment (Day 31). Lymphocyte proliferation decreased in FREE and FLEX-kept sows on Day 31, compared to Day 30, indicative of an acute stress response.

Figure 4 represents the neutrophil-to-lymphocyte ratio for sows kept in the FREE system only. As days of gestation increase, the number of neutrophils also increases, indicating an acute stress response.

Figure 5 shows that litter performance was impacted by environment. Sows kept in the FLEX stall had greater piglet mortality compared to sows in the other two groups. The number of male offspring was higher among sows kept in either the FLEX crate or the FREE system.

Sows weren't placed in treatments until Day 30 of gestation and sex is determined before this, so the treatments did not influence sex per se. But the environment may influence the “survival of the fittest,” suggesting that female mortality may be greater in FLEX- and FREE-kept sows.

Researchers: Janeen L. Salak-Johnson and Ashley DeDecker, both of the University of Illinois. For more information, contact Salak-Johnson by phone (217) 333-0069, fax (217) 333-8286 or e-mail