Highlights of what stakeholders need to know about the scientific knowledge that has supported the Code of Practice for the Care and Handling of Pigs

The process of Code of Practice development is coordinated by the National Farm Animal Care Council (NFACC), the lead national organization for farm animal care in Canada. NFACC brings together farmers and other agriculture and food sector representatives, animal welfare groups, enforcement and government under a collective decision-making model for advancing farm animal welfare.

For all stakeholders, an important part of understanding the knowledge basis that underlies the Pig Code is to understand the findings from the Scientific Committee review, which played a vital supporting role in the Code development process.

This Executive Summary: The Science of the Pig Code is designed to help deliver this knowledge. It provides highlights of key information from the Scientific Committee report on priority welfare issues.

The complete Scientific Committee review report, along with more information on all aspects of the Pig Code and the Code development process, is available at www.nfacc.ca/codes-of-practice/pigs.

Executive Summary: The Science of the Pig Code

Five key areas of new knowledge

What the science says on the key issues

Sow Housing

Gestation stalls are a focal point of the animal welfare debate as it relates to pig production. While they are common and widely used in the Canadian industry, there is mounting pressure to shift away from the use of stalls toward greater use of alternative grouped housing approaches.

The Scientific Committee reviewed the pig welfare research related to gestation stalls and grouped housing options, providing an assessment of the known research conclusions for each.

What the science says. Viable group housing alternatives have emerged. It is possible to achieve equal or better productivity and health in group-housing systems compared to individual gestation stalls provided that they are well designed and managed.

Gestation stalls do offer important welfare benefits. The primary one is that they protect sows by preventing aggression among the animals. Also, the controlled environment that stalls provide allows producers to maximize the monitoring and nutritional care of the animals.

However, there are scientifically supported negative welfare aspects of stalls. First, they limit the sows’ freedom of movement. Second, they limit the sows’ ability to exhibit natural behaviours. These two conditions are now commonly accepted in the scientific community as essential elements of sound welfare practices.

Sows spending long time periods in stalls are limited in their social interactions, foraging and exploratory behaviours. They are also limited in exercise, resulting in reduced muscle and bone strength. Additionally, sows in stalls exhibit less comfortable resting time and more “stereotypic” behavior – i.e. repetitive movements or actions that can indicate restlessness, stress, lack of comfort, general frustration or other negative welfare implications.

Science and related innovation have advanced to the point where there are viable alternatives to the use of gestation stalls. Grouped, a.k.a. loose housing systems, allow advantages in terms of freedom of movement and the opportunity to exhibit natural behaviours. However these systems do come with their own unique sets of challenges, including welfare concerns related to increased risk of animal aggression. They must be well structured and managed to reduce this risk of aggression.

Pain management

Another focal point of the animal welfare debate is pain management, particularly for procedures such as castration. The review of the Scientific Committee explored practical options for pain control.

What the science says. The science confirms that castration is a painful experience. Post-operative pain is also a concern for at least several hours after the procedure is completed. However, the review found that while there are significant options to mitigate pain at both stages, not all are practical within a typical management framework. Among anesthetic options, injection of a local anesthetic such as lidocaine into the testicles at least three minutes prior to surgery was identified as the most practical and safe method to reduce the pain associated with the surgery. However, this approach requires handling the pigs twice which is not typically practical and can also be a potential negative from a welfare perspective because it means increased handling of the animals which can result in longer overall periods of discomfort or stress. 

The use of general anesthetic was found to be undesirable because it puts the animals at increased risk of danger during the recovery phase. Immunizing animals against testicular growth is another option that is an effective means of eliminating boar taint; however, use of this approach requires adding a monitoring process to detect animals that have not been immunized or that were improperly immunized.

The findings related to the use of analgesics were more positive. Injection with ketoprofen or meloxicam shows clear value to help control post-operative pain that can be administered without unduly disrupting the flow of production. More research is required to better evaluate the exact effectiveness and duration of these options, but there is enough evidence to indicate they do provide significant pain mitigation.

Space Allowances

The science review explored three key aspects involved in determining what is adequate space, including how space affects the animals’ biological function, affective states and ability to express natural behaviours.

What the science says. The approach of the Scientific Committee included looking at the different needs of different types and sizes of animals at different stages of production.

Gestation stalls – When using gestation stalls, the review observed it is critical that pregnant gilts and sows are kept in stalls that are appropriate to the size of the individual animal. Specifically, the science supports that stalls should be large enough so that sows can:

  • Stand up at rest without simultaneously touching both sides of the stall.
  • Lie down without their udders protruding into adjacent stalls.
  • Stand up without simultaneously touching both ends of the stall.
  • Stand up without touching the top bars.

It noted that conventional gestation stalls [58 – 60 cm (22.8 – 23.6”)] may not be wide enough for larger sows to lie laterally, especially towards the end of the gestation period.

Nursing and grower-finish – For nursing and growing-finishing pigs, a major focus of the Scientific Committee was to use the body of knowledge available to develop updated formulas for determining proper space allowance. This included identifying two points at which welfare is compromised, in terms of behavior and productivity. The Scientific Committee report provides information to support decision making that upholds sound welfare while also taking into account economics and current practices. The updated formulas provide a more sophisticated basis for producers to pinpoint what an effective balance that protects welfare while also considering overall production efficiency.

Social management of sows

The science relative to the social management of sows informs the discussion on gestation stalls and group housing, as well as on space allowance.

What the science says. The science provided the following insights: • Management strategies have been developed that can be used to reduce aggression at key periods when risk of aggression is high, such as during periods when establishing social hierarchy and when competing for food. • Avoidance behaviour may be a strategy that sows use to prevent being involved in agonistic interactions. As a result, designing pens in a way that allows sows to perform this behaviour more easily and to provide sufficient surface area to do so may be important to reduce aggression. • Sow age, social rank and previous experience, along with group stability and size, all impact how well animals integrate and perform in new groups • Mixing sows prior to implantation, if managed well, need not affect reproductive performance.

Methods of Euthanasia

The Scientific Committee revisited this chapter after developing its initial report, in order to include new research results.

What the science says. The science review found that when euthanasia is appropriate, accomplishing this task effectively and humanely requires applying a method that ensures 1) instantaneous loss of consciousness and 2) rapid death without the animal recovering any consciousness.

When applied with sufficient force, blunt trauma and non-penetrating captive bolt are effective methods of euthanasia for suckling piglets that result in immediate unconsciousness and death.

Penetrating captive bolt is effective as a single step method for euthanasia of pigs under 120kg that is safe for handlers and is cost-effective. For mature sows and boars, penetrating captive bolt causes loss of consciousness, but a secondary step – exsanguination – is necessary to ensure death.

When properly executed, gunshot to the head is also effective for euthanasia; however human safety is a concern.

View the Scientific Committee report for complete information

This Executive Summary: The Science of the Pig Code highlights key findings from the Pig Code Scientific Committee Report

The work of the Scientific Committee supports but does not determine the final wording of specific requirements and recommendations within a Code of Practice.

Code of Practice updates initiated from 2010 to 2013 are part of the project: Addressing Domestic and International Market Expectations Relative to Farm Animal Welfare
 – a project made possible through Agriculture and Agri-Food Canada’s Agricultural Flexibility Fund, as part of Canada’s Economic Action Plan.