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Feature: Interview with Professor Sandra Edwards

Sandra Edwards is the Professor of Agriculture at the School of Agriculture, Food and Rural Development at the University of Newcastle. She is a leading international expert on pig husbandry and welfare and was one of the keynote speakers at the International Pig Welfare Conference in Copenhagen in April.


Professor Sandra Edwards,
University of Newcastle

Here are her responses to a series of questions put to her by Pig Industry Matters, addressing some of the main pig welfare issues debated at the recent conference.

What effect has the group housing of pregnant sows on pig welfare?

Group housing provides the ability for sows to move around and socialise. Exercise improves bone and muscle strength, and fitter animals may have faster and less problematic farrowings. Having greater space allows for a more diverse environment and the possibility to design housing which can better meet the animals’ needs for foraging and exploration. This reduces the risk of development of abnormal stereotyped behaviours which are more commonly seen in individual confinement systems.

Since pigs are social animals, having free interaction with others in the group can also be considered to facilitate natural behaviours. However, this also brings the risk of undesirable aggression and social stress, especially at times of mixing and if there is inadequate space for avoidance and escape. Furthermore, aggression can be increased if the animals must compete for food or are not fully protected whilst eating. Good housing design and management are essential to minimise these risks and deliver both good welfare and good performance in group systems.

How important is the provision of ‘enrichment materials’ on pigs' welfare, and are there any indications that pigs in Denmark or Germany are suffering from stimulation deficit?

Enrichment materials are of great importance for pig welfare, because the pigs have evolved with a strong behavioural need to exhibit exploratory and foraging behaviours. If the environment does not provide appropriate enrichment materials towards which these behaviours can be directed, then other types of undesirable behaviour can develop.

In the case of pregnant sows, this can take the form of stereotyped oral behaviours, or of increased aggression and vulva biting in group systems. In growing pigs, the exploratory behaviour is directed instead to pen mates, increasing the risk of tail, ear and flank biting.

There is also increasing evidence that lack of enrichment in early life can reduce the ability of animals to cope with challenges when they are older and predispose them to show such injurious behaviours. The widespread persistence of these behavioural problems in commercial farms suggests that the enrichment currently provided could often be improved. Whilst the provision of straw is one solution, this is not always possible for reasons of availability, biosecurity or manure management. A range of other types of effective enrichment have been researched, such as jute sacks or fresh wood, and ideas can be found from research undertaken by the University of Helsinki.

Straw dispenser

Is there a better alternative to surgical castration which is the method still commonly used in both Denmark and Germany to reduce the risk of ‘boar taint’?

Castration of male pigs is still considered necessary in most countries to avoid the risk of ‘boar taint’ in the meat. Historically this has been carried out on the young piglet as a surgical procedure without anaesthesia or analgesia. It is now clear that this procedure is very painful and that some degree of discomfort persists for several days.

The 2010 European declaration on alternatives to surgical castration of pigs was a voluntary agreement between stakeholders, including those in Denmark and Germany, that surgical castration of pigs should be abandoned by 1 January 2018. Some countries, such as the UK, have already largely abolished all castration and other countries, such as the Netherlands are now moving rapidly in this direction. However, not all markets will yet accept meat from entire males, especially from production systems with high slaughter weights.

Whilst progress towards achieving the goal of non-castration is being made through genetic selection and nutritional interventions to reduce boar taint, coupled with development of rapid automated methods for taint detection and on-line carcass sorting, there is still uncertainty about how soon these can deliver a system for entire male production that will be fully accepted.

The alternative approach of immunological castration, involving two injections to the pig later in life to stop production of the hormones causing taint, is now technically feasible and being implemented in some countries. However, there are still concerns from many retailers about consumer acceptance of this technology. As an interim measure, the continuation of surgical castration, but only with anaesthesia and prolonged analgesia to protect piglet welfare, may be necessary whilst alternative solutions are perfected.

What is the purpose of tail docking and does it have any effect on the pigs' behaviour?

Tail docking is carried out on young piglets because there is clear evidence that having a docked tail reduces the risk of receiving injury from tail biting in later life. Many farmers believe that this procedure causes little pain to the piglet and is justifiable because of the serious welfare and economic problems that tail biting can cause. However, scientific study suggests that acute pain does indeed occur when the tail is docked, and there is a possibility of longer term pain from the damaged nerves in the tail stump. Even if such pain can be shown to be negligible, or prevented with analgesia, it is increasingly unacceptable to consumers that the integrity (wholeness) of animals is not respected.

Some countries, for example Sweden, have already abolished tail docking and, whilst the prevalence of tail biting is higher than in docked animals, have developed systems to minimise risk by appropriate housing and management. The risk factors for tail biting have been widely studied and tools for risk evaluation and risk reduction now exist to help farmers.

In the future, genetic selection of pigs with lower tail biting predisposition and improvement in pen enrichment provision offer further risk reduction potential, which could make the production of pigs with intact tails more acceptable in commercial practice.

Is it important for high pig welfare that the sows are loose in the farrowing unit?

The farrowing crate has been widely adopted because of the benefits it offers for piglet survival: control of sow lying to protect against crushing, ability to provide localised heat at the birth site and safety for stockworkers when they intervene to assist weak piglets. These benefits become even more important with the recent development of hypoprolific sows, which produce smaller less viable piglets and require much more staff input for fostering between litters.

However, these benefits come at the expense of sow welfare, because the confinement of the crate causes stress to the sow by preventing her from expressing her strongly motivated nest-building behaviour just before farrowing, and by limiting her freedom of movement throughout lactation. Because of these concerns for sow welfare, some countries, for example Sweden, have already banned the use of farrowing crates and there is consumer pressure in many other countries to follow this lead.

Alternative loose farrowing systems are being developed and trialled in a number of countries and information on these can be found at a Free Farrowing information resource. Whilst some show good potential, their capital cost is higher than crates and there has been variability in piglet survival under commercial conditions, highlighting the importance of correct design detail and management. As a possible interim measure in the move to free farrowing, systems with temporary confinement of the sow for just a few days after the birth of the piglets have now been developed. Whilst not the perfect solution if nest building is still prevented, they allow for better piglet care in the most critical period, combined with greater sow freedom for the majority of lactation, which can give added benefits for milk yield and weaning weights.

Free Farrowing Pen