Providing greater freedom of movement to stall-housed sows

Identifying how sows value freedom of movement compared to a resource — such as food — helps to gauge understanding of the sow’s motivation for a period of freedom of movement.

May 29, 2018

5 Min Read
Providing greater freedom of movement to stall-housed sows
A sow runs down the alleyway between stalls after exiting the stall. Christina Weese for the University of Saskatchewan

By Yolande Seddon, Michaella Barnes and Mariia Tokareva, University of Saskatchewan; and Ed Pajor, University of Calgary
A research project led by researchers at the University of Saskatchewan’s Western College of Veterinary Medicine, with collaboration from researchers at the Prairie Swine Centre and the University of Calgary, is aimed to determine whether stall-housed sows are motivated to access greater freedom.

The rationale for the research stems from the 2014 change in the requirements of the nationally developed guidelines the Canadian Code of Practice for the Care and Handling of Pigs.

The updated code required that all barns newly built, renovated or brought into use for the first time after July 1, 2014, house bred gilts and sows in groups. However, existing stall barns in good working order can continue to house bred pigs in gestation stalls until a barn renovation is required.

As of July 1, 2024, the national code will require that all bred gilts and sows continuing to be housed in gestation stalls are provided with the opportunity to turn around and exercise periodically, or have access to other means that allow a greater freedom of movement. The code requires that the suitable options as to what constitutes a greater freedom of movement are clarified by participating stakeholders by July 1, 2019, as informed by scientific evidence. However, the science on what might qualify as greater freedom of movement is sparse.

The research team is working to provide scientific evidence that will help to establish whether opportunities for greater freedom of movement are valued by stall-housed sows — and whether periodically providing greater freedom of movement will produce measurable benefits for sow welfare.

Previous studies have determined that sows exercised at regular intervals show physiological changes related to improved health. However, animal welfare also depends on how the individual animal feels, and there is limited research on whether stall-housed sows value opportunities for a greater freedom of movement. While this may seem like an obvious question to some, it becomes important considering that greater freedom of movement is the main approach being proposed for improving the welfare of sows in stalls.

The research team will try to answer this question by first conducting a motivation study — a scientific method used to determine how important the choices, or features, of the environment are to animals.

The research uses an operant panel. This device determines the strength of an animal’s motivation by allowing the animal to make a choice that triggers a reward.

The operant panel consists of a sheet of metal, mounted with two buttons, attached inside the gate of the sow’s stalls (Figure 1).


Figure 1A: The operant panel containing two buttons, with a metal divider in between so the sow has to make a defined choice.


Figure 1B: The operant panel in position over the stall gate, so making a defined choice to press one button.

Sows are trained to press one of the buttons; the reward for doing so being that the sow is released from the stall for three minutes of free movement in the alleyway between stalls (see photo at the top of this article).

Training continues so sows learn that they must press the button an increasing number of times to keep receiving time out of the stall for freedom of movement. Once sows have learned to press the button up to nine times, the sows begin to be tested daily for their motivation to exit the stall, with the number of button presses that a sow must perform to exit the stall increasing each day.

When the number of button presses increases to a point where the sow stops pressing, the total number of button presses she achieved is a measure of her motivation to exit the stall. Following testing for freedom of movement, sows are retrained to associate pressing the button with receiving a small quantity of feed. Testing continues to determine the number of button presses the sow will make to obtain a food reward — a measure of her comparative motivation.

By recording the number of times the sows are willing to press the button in each situation, the researchers can measure how hard the animals will work to gain access to each reward.

Identifying how much sows value freedom of movement compared to a resource that is known to be valuable — such as food — helps to gauge further understanding of the strength of a sow’s motivation for a period of freedom of movement.

Providing periodic access to a greater freedom of movement helps to alleviate animal confinement in stalls. However, it also needs to be considered, how access to a greater freedom of movement will benefit sow welfare if given periodically at a level that may be practical to implement.

The research will explore this question through a gestation trial that evaluates measures of sow welfare, productivity and piglet viability, as a measure of gestational stress effects, across three treatments.

i) sows housed in stalls throughout gestation,
ii) sows housed in stalls and given periodic exercise (once per week) and
iii) sows housed in groups for gestation. Results will be available in 2019.

Despite an increasing number of countries that are converting to group housing for gestating sows, where stalls continue to be used in the production cycle, the well-being of stall-housed sows should be considered. Alternative methods to improve the welfare of stall-housed sows other than exercise could be considered and include provision of pig appropriate enrichment in the stall, provision of a fiber diet to improve satiety and improvement of the lying comfort.

The authors would like to thank the Agriculture Development Fund Saskatchewan for funding this research.

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