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Keeping pigs busy could improve welfare

prairie swine pigs

Researchers are working with pigs at the Prairie Swine Centre to determine what modifications to their environment will keep them healthy. Photo by Victoria Kyeiwaa.

I have travelled halfway around the globe from my home in Ghana to look for ways to improve the management of sows here in Canada.

As a University of Saskatchewan master’s student working at the Prairie Swine Centre (PSC), my research focuses on enrichment measures for pigs – specifically sow enrichment, which could include a number of benefits to the pig’s environment such as increased pen space.

Funded by Agriculture and Agri-Food Canada (AAFC), this research is part of a larger Swine Innovation Porc project that’s led by Dr. Laurie Connor at the University of Manitoba (U of M). Ongoing studies at PSC and the U of M are aimed at developing effective environmental enrichment for group-housed sows that would be economically viable for the pig industry and would guide producers in decision making.

The farm-level interest in sow enrichment has been driven by the revised Code of Practice for the Care and Handling of Pigs. It includes a requirement that all pigs should be provided with “multiple forms of enrichment that aim to improve the welfare of the animals.”  This code requirement, along with the trend towards group gestation housing, has created a need for research in this area.

While many different forms of enrichment materials have been studied, most research has focused on piglets and growing pigs. These studies have shown that giving appropriate enrichments to growing pigs can result in reduced aggression, reduced fear, improved growth and fewer behavioural vices such as tail-biting.

While similar benefits can be expected for sows, older animals are different and generally prefer manipulable and destructible enrichments over simple objects. Some commonly used enrichment materials are straw, chains, wood, rope, mushroom compost, wood shavings, garden hose, peat moss and rubber balls.

Although European research has identified straw and other malleable and consumable materials as being optimal, there’s been a reluctance to provide such materials in North America.

“Straw has been effective in grower-finisher pigs but there is an increased risk to biosecurity,” says Dr. Jennifer Brown, an ethology research scientist at PSC and my supervisor. “In this study, we included straw as a comparison treatment to the other enrichments. Small amounts of high fibre materials such as chopped or pelletized straw can be provided in a rack or hopper, for example, and will increase satiety (feeding satisfaction) in sows as well as providing enrichment.”

Sows in stalls show stereotypies or abnormal behaviours such as bar biting, continuous drinking and vacuum/sham chewing – chewing motions with no food present. These behaviours have no clear function, and they’re seen as potential indicators of frustration, boredom, fear and distress.

Sows in group housing also show some of these abnormal behaviours, especially ear or tail-biting, bar biting and overt aggression – behaviours that can increase the chance of abortions.

“Provision of environmental enrichment could potentially reduce or even eliminate these behaviours,” explains Brown. “But our question is, what types of enrichments do sows prefer?”

The sows in the study are offered three options for enrichment materials: rope, small amounts of straw and wood on chains. Sows in a control group receive no enrichment materials.

Because pigs are social animals in a social environment, subordinate animals may be bullied and driven away from available resources by dominant animals. As a result, the study is also investigating the influence of social status on the animals’ use of enrichment materials.

The researchers determine social status through a feed competition trial that enables them to select six focal sows per group – three dominants and three subordinates – for additional data collection. By observing the behaviour of both dominant and subordinate sows, researchers can determine if all sows — no matter what social status — can benefit from enrichment use.

Since a common problem with enrichments is that animals lose interest in them over time, our research team is also determining whether it’s beneficial to provide the same enrichments or if regularly rotating them increases their interest and value to the sows.

Using cameras mounted over the pens, the researchers are examining time lapse photos taken on selected days to determine the level of enrichment use as well as the activities and postures of sows. They’re also using live observation to record any stereotypic behaviours, and they’re determining levels of aggression by examining the animals and recording skin lesion scores that range from zero (no injury) to three (severe injury).

Accelerometers — similar to the pedometers that people use to record fitness activities — record the mobility of the animals as a way to compare the activity levels of dominant and subordinate sows. In addition, saliva samples taken in early, mid- and end of each trial are used to determine cortisol levels – a reliable indicator of stress levels in animals.

While the benefits of enrichment are well known, it’s still unclear which specific enrichments are suitable at each stage of production and which methods are best for presenting them. Our research will help to fill these gaps in knowledge about the use of enrichments for sows. It will also form the basis for practical recommendations that can benefit sows and help producers meet the code of practice requirements.

Enrichment is a new area for Canadian pig producers who need time to clarify what enrichment means as they begin implementing measures that will benefit their herds.

“Enrichment can help to reduce aggression and stress and improve physiological function for all ages of animals,” says Brown. “Clearly there is a benefit to the industry and providing enrichment will also help to address consumer concerns about barren conditions in pig housing. Once producers get comfortable with the concept of enrichment, I’m sure we will see them taking the lead on this and coming up with some great ideas.”

Victoria Kyeiwaa is a master’s student in the U of S College of Agriculture and Bioresources whose research project was supported by Agriculture and Agric-Food Canada (AAFC). Victoria’s story is part of a series of stories written by WCVM summer research students. 

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