Providing objects or substrates for proper investigation and manipulation and keeping pigs occupied in non-harmful behaviour are the main aims, according to the report. The key properties of the objects are that they are destructible, edible, nutritious and kept dung-free.

For thousands of years, pigs have rooted to find enough food to stop them being hungry, and to find the right balance of nutrients to keep them healthy. Today's commercial pigs providing a concentrated diet still have this drive to root and an inability to carry out this activity is known to be linked to tail-biting.

The BPEX/Bristol report identifies three paths to tail-biting:

• Boredom – pigs have insufficient material to root and chew, so they chew pen fittings and each other. The tail and ears are chewable targets. The key to preventing this is to provide proper enrichment to root and chew instead
• Frustration – pigs cannot compete shoulder-to-shoulder with other pigs to reach food, water and other resources. The tail is an easy target and helps the pig to reach what it wants. The key is to check that all pigs can reach all resources.
• Fanatics – usually pigs that had a growth check at weaning, possibly due to problems digesting protein. They spend much more time tail-biting than other pigs. It is important to keep an eye on these individuals and remove them if tail-biting looks likely.

Key properties to keep pigs busy are that they need to be destructible, edible, chewable and be kept clean. Pigs soon become bored with indestructible objects and chewable objects keep their interest. Pigs chew and swallow what they find so one of the roles of rooting is to fill the gut, while pigs with higher gut-fill have less need to root. Pigs get a benefit from eating or chewing in terms of vitamins, fibre etc. It is vital to keep the object clean: pigs quickly lose interest in dung-covered objects.

Options for Solid-Floor Housing Systems

Straw offers a number of benefits: it is a manipulable and rootable material, it provides thermal insulation and physical cushioning. Straw may be provided simply as bedding. Alternatively it can be placed in dispensers/racks, bundles or compressed blocks or 'logs'. Straw is most effective when some new straw is added daily and the straw is long, not chopped.

Other materials that can be provided alongside straw include hay, wood, sawdust, mushroom compost, peat or a mixture of such which does not adversely affect the health of the animals.

Straw offers additional benefits

Options for Slatted and Part-Slatted Accommodation

Straw is not a practical option for fully slatted systems so producers must provide other enrichment toys or materials.

Pigs respond to novelty and get bored after a while with the same stimuli, therefore different enrichment toys should be rotated to maintain novelty.

The BPEX KT team trialled hanging BiteRites and fixed Funbar stations on a number of units across England: both toys encouraged interaction by the pigs and the BiteRites received a higher level of general interest than the Funbar stations.

Paper sacks and other disposable paper or cardboard materials thrown into grower/finisher pens can be an effective way to occupy pigs. The novelty and effectiveness of these can wear off quickly, but paper and cardboard materials can be added from time to time to supplement other more permanent toys, particularly to distract pigs if a tail-biting outbreak has just started or is suspected.

BiteRite

Other toys can be provided alongside, such as balls, traffic cones and vegetables. Chains which include other objects, such as wood or alkathene pipe, can be just as effective, are acceptable and can make use of existing enrichment.

Hard objects alone do not constitute full enrichment – pigs should also be provided with something soft and malleable/destroyable.

Objects are harder to root in but can be good to chew and manipulate. Possibilities include: wood, logs, rope, tough dog chews, alkathene pipe, cloth strips, rubber sheets, paper and cardboard. Producers should watch out for staples in card and paper, thorns in twigs and branches, chemical treatment of wood sources and naturally poisonous woods.

Food Enrichment

The principle is to keeps the pigs occupied for much longer than when all food is supplied in one place or in meals. It is also a more natural behavioural activity, leaving less time to chew the pen or each other.

The feed may be from the daily ration, by being mixed with daily fresh straw, or on the floor provided it is clean enough and in small groups, in Edinburgh food-ball or strong dog toy, in wood or other destructible object. A roller in liquid feed helps to encourage rooting behaviour.

Alternatively, novel foods can be introduced, such as herbal mineral blocks, salt licks, root vegetables, grass (cut or as turf or silage) or hedge trimmings. They may be scattered in small pieces or whole, or attach to pen sides, put into a rack.

To help keep objects dung-free, they may be suspended, attached to the wall or strong pen fittings. A small step or low wall (such as a railway sleeper) between lying and dunging areas can help keep dung and bedding separate.

The report that environmental enrichment can also be provided in the form of a broom head or post for scratching, or a radio playing, which reduces pigs' reactivity to sounds and improves the environment for stockpeople.

Feed provided in toy

Enrichment Legislation and Welfare Standards

The final section of the BPEX/Bristol report outlines the legislation on environmental enrichment and assurance scheme standards.

The Welfare of Farmed Animals (England) (Amendment) Regulations 2003 (S.I. 2003 No. 299), Schedule 6, Part II, paragraph 16 states that: 'To enable proper investigation and manipulation activities, all pigs must have permanent access to a sufficient quantity of material such as straw, hay, wood, sawdust, mushroom compost, peat or a mixture of such which does not adversely affect the health of the animals.'

The Defra code states that 'Environmental enrichment provides pigs with the opportunity to root, investigate, chew and play. Straw is an excellent material for environmental enrichment as it can satisfy many of the pigs’behavioural and physical needs. It provides a fibrous material which the pig can eat; the pig is able to root in and play with long straw; and, when used as bedding, straw can provide the pig with physical and thermal comfort.

'Objects such as footballs and chains can satisfy some of the pigs' behavioural needs, but can quickly lose their novelty factor. The long-term use of such items is not, therefore, recommended unless they are used in conjunction with materials such as those listed above, or are changed on a weekly basis.

'The lying area should always be kept dry and pen floors, including the dunging area, should be drained effectively. Where bedding is provided, this must be clean and dry, regularly topped up or changed, and not detrimental to the health of the pigs.'

The latest Red Tractor Assurance Scheme standards for manipulable material came into force in April 2010. Key changes to the standards were that:

• Chains alone are not acceptable
• Tyres are not acceptable as some may contain wire which could hurt the pigs
• Objects must be shown to be of interest to the pigs, i.e. not fouled
• Objects must be within the pigs' reach

Below are some simple criteria to think about when choosing the best enrichment objects for pigs: the six Ss.

• Safe
• Sanitary
• Suspended
• Soft
• Simple
• Site

The BPEX/Bristol report concludes: 'Enrichment is just one aspect of a pig's environment and it is important to get other aspects right too, including ventilation, nutrition, health, water provision and stocking density. All will contribute to improved production and reduced risk of vice.'

Further Reading

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You can view the full report by clicking here.