Pig welfare guidance

Guidance about the needs of pigs and how to meet these needs in accordance with good practice.



Paragraph 16 of schedule 6 of the Welfare of Farmed Animals (Scotland) Regulations 2010 states that:

16. 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.

88. All pigs must have permanent access to enrichment materials which provide pigs with the opportunity to engage in proper investigation, manipulation and foraging activities. Research shows that provision of sufficient, suitable enrichment has a positive impact on both physical and mental health and welfare and reduces the likelihood of potentially damaging abnormal behaviours. In order to be effective, enrichment materials should enable pigs to fulfil their essential behavioural needs without compromising their health. They must be safe, hygienic and should have one or more of the characteristics set out below. More than one type of enrichment material may be required to ensure that all of the pigs’ needs are met, and to provide the pigs with an element of control and choice.

89. It is important to note, however, that enrichment materials are an addition to the pigs’ environment. They are not a substitute for a poor environment and as such cannot address such deficiencies. It is important that the pigs’ environmental needs are met, regardless of the enrichment opportunities provided.

90. Enrichment materials should be:

a) edible— so that pigs can eat or smell them (possibly with some nutritional benefits);

b) chewable— so that pigs can bite them;

c) investigable— so that pigs can investigate them; and

d) manipulable— so that pigs can change their location, appearance or structure.

91. Straw and dried grasses such as hay are examples of optimal materials for environmental enrichment, as they can satisfy all of the characteristics described above when they are provided in sufficient quantities and replenished as necessary. They are fibrous materials which the pig can eat; the pig is able to root in and play with them; and, when used as bedding, these materials can provide the pig with physical and thermal comfort. Various straw types can be suitable for enrichment but some are less suitable for bedding compared to cereal straws such as barley, wheat and oats. The key consideration is the quality of the material used, for example not dusty, wet or mouldy. It is acknowledged, however, that some existing buildings cannot cope with this type of enrichment in optimal quantities. Examples of other enrichment materials are given below.

92. The following materials are not recommended due to potential health or environmental risks or other concerns: mushroom compost, peat, or novel sources of bedding such as “green” bedding. Although mushroom compost and peat are referred to in the legislation as examples of suitable materials, there are now recognised health risks associated with these.

93. Objects such as footballs and chains can satisfy some of the pigs’ behavioural needs, but only in the short term as they can quickly lose their novelty factor. They are therefore not considered suitable as the only form of enrichment material. If they are provided, other materials should also be available to meet all the pigs’ enrichment needs. Branched chains are preferable to single chains, as they provide more complexity and are therefore more manipulable. However, they are still only of marginal interest and so should only be used with other materials which meet all the pigs’ enrichment needs. Rotation of different enrichment materials and objects can also help to maintain the animals’ interest in them.

94. Enrichment materials have been categorised as follows, according to how well they meet the characteristics:

a) optimal materials—materials possessing all the characteristics listed in paragraph 90 and therefore can be used alone, as long as they are provided in sufficient quantities and are replenished as necessary;

b) suboptimal materials—materials possessing most of the required characteristics and therefore should be used in combination with other materials (optimal or suboptimal) possessing the other required characteristics to improve the enrichment experience of the pig; and

c) materials of marginal interest—materials of limited interest to pigs, which are not considered capable of fulfilling their essential needs for enrichment purposes, and therefore should only be used in conjunction with optimal or suboptimal materials covering all of the required characteristics.

95. The following table, which is not an exhaustive list, provides guidance on the suitability of commonly used enrichment materials. Further guidance is also available from AHDB (see Annex 3).

Suitability of materials for providing environmental enrichment

Materials: Cereal straws and dried grasses

Provided as: Bedding

Suitability of environmental enrichment material: Optimal – but should be provided in sufficient quantities and replenished as necessary.

Additional information: Meets all the requirements of appropriate enrichment material. Most of these also provide appropriate thermal and physical comfort needs as bedding.

Risks (always check for toxicity): Competition if insufficient for all pigs. Can get dirty or wet, may need frequent replenishment. Some straws less suitable as bedding materials.

Materials: Silage, root vegetables (N.B. parsnips are toxic to pigs)

Provided as: Novel food source

Suitability of environmental enrichment material: Optimal – if permanently available / constantly replenished.

Additional information: N/A

Risks (always check for toxicity): Provide in appropriate amounts to avoid competition and over-feeding. Ensure vegetable type is safe to eat for the quantities provided.

Materials: Cereal straws and dried grasses

Provided as: Rack or in dispenser

Suitability of environmental enrichment material: Optimal – if permanently available / frequently replenished. Suboptimal if not constantly available. Also does not allow for rooting unless/until enough is pulled from the racks.

Additional information: More hygienic than when provided as bedding.

Risks (always check for toxicity): Competition if insufficient dispensers and/or insufficient daily supply for all pigs.

Materials: Wood shavings, sawdust

Provided as: Bedding

Suitability of environmental enrichment material: Suboptimal

Additional information: May be complemented by edible / manipulable materials.

Risks (always check for toxicity): Ensure safe to use – an untreated wood source, so no metal content.

Materials: Sand

Provided as: Bedding

Suitability of environmental enrichment material: Suboptimal

Additional information: May be complemented by edible / manipulable materials.

Risks (always check for toxicity): Ensure safe to use.

Materials: Shredded paper

Provided as: Bedding / nesting material

Suitability of environmental enrichment material: Suboptimal

Additional information: May be complemented by edible / manipulable materials.

Risks (always check for toxicity): Ensure safe to use and metal-free. Printed or recycled is not recommended due to toxins in the ink. Easily becomes soggy and coagulates into large unmanipulable masses (papier mache).

Materials: Soft, untreated wood, cardboard, natural rope, hessian sack

Provided as: Object

Suitability of environmental enrichment material: Suboptimal

Additional information: May be complemented by edible / investigable materials. If using rope, try tying knots in it so that pigs cannot bite off long pieces that could end up in the slurry system.

Risks (always check for toxicity): Competition if insufficient for all pigs.

Materials: Compressed straw in cylinder

Provided as: Object

Suitability of environmental enrichment material: Suboptimal

Additional information: May be complemented by investigable / manipulable materials.

Risks (always check for toxicity): Competition if insufficient for all pigs.

Materials: Sawdust briquette (suspended or fixed)

Provided as: Object

Suitability of environmental enrichment material: Suboptimal

Additional information: May be complemented by edible / investigable / manipulable materials.

Risks (always check for toxicity): Competition if insufficient for all pigs.

Materials: Chain, rubber, soft plastic pipes, ball, hard plastic, hard wood

Provided as: Object

Suitability of environmental enrichment material: Materials of marginal interest

Additional information: Should be complemented by optimal or suboptimal materials to meet all the edible / chewable / investigable / manipulable requirements.

Risks (always check for toxicity): Interest quickly lost. Suspending objects prevents soiling. Change regularly.

96. Enrichment needs to sustain interest and should always be available and in sufficient quantity to allow all pigs the opportunity to interact. Materials which do not have all of the defined characteristics are less likely to achieve this and may need replacing or changing more often. If enrichment materials are not being used by the pigs, this probably indicates that they are not meeting the intended purpose.

97. If the enrichment is provided as bedding, it should be a material which is hygienic, clean, dry and safe to use for bedding purposes, and should be provided in sufficient quantity to maintain interest. Improved enrichment in straw or other materially-bedded environments may include regularly adding large bales that the pigs can pull apart themselves.

98. Where the provision of larger volumes of enrichment material is limited due to the floor and slurry removal systems, owners / keepers should ensure that what is provided is replenished sufficiently often to maintain interest.

99. The enrichment material’s frequency of renewal, its accessibility, and quantity are all key factors in maintaining a pig’s interest, and, where appropriate, physical checks as well as visual checks may be needed. Re-directed chewing behaviours towards other pigs or non-enrichment materials, such as faeces or equipment, should be discussed with a veterinary surgeon as this may suggest the enrichment material is inadequate or ineffective and should therefore be reviewed, or other contributing factors may need to be addressed. See paragraphs 137 to 156.

Ventilation and temperature

Paragraph 13 of schedule 1 of the Welfare of Farmed Animals (Scotland) Regulations 2010 states that:

13. Air circulation, dust levels, temperature, relative air humidity and gas concentrations must be kept within limits which are not harmful to the animals.

Paragraph 17 of schedule 6 of the Welfare of Farmed Animals (Scotland) Regulations 2010 states that:

17. Pigs must not be kept in an environment which involves maintaining high temperatures and high humidity (known as the “sweat-box system”).

100. Effective ventilation is essential to the wellbeing of the stock as it provides fresh air, removes noxious gases and aids in controlling temperature. High ammonia levels have negative impacts on pig health as well as on the health of those who care for the pigs. It is also important to avoid draughts: in addition to having an impact on pig health, welfare and comfort, draughts can trigger aggressive behaviour in pigs. See also paragraphs 145 to 147.

101. The tables below set out the ideals of temperature in housing for each category of pig, and ideals of other environmental measures. These should be taken as a guide to ideal target ranges only rather than definite limits. It is just as important to observe the behaviour of the pigs in order to determine whether the environment is suitable for them and, if not, to take appropriate action. For example, different breeds of pig, or pigs with different growth rates, might prefer slightly different temperatures.

Category of Pig Temperature
(°C) (°F)
Sows 15 - 20 59 – 68
Suckling pigs in creeps 25 - 30 77 – 84
Weaned pigs (3 – 4 weeks) 27 - 32 81 – 90
Later weaned pigs (5 weeks +) 22 - 27 71 – 80
Finishing pigs up to 70 kg 15 - 21 59 – 70
Finishing pigs over 70 kg 13 - 18 55 – 64

Ammonia: Less than 10 ppm

CO2: Less than 3000 ppm

Relative Humidity: 45-75%

102. In some cases, it might be difficult to maintain these environmental measures. For example, the upper limits of temperature for finishing pigs might be hard to maintain in the summer months. Advice is therefore given below on how to adapt the environment to make it more acceptable for the pigs, despite the ideal measures not being met. Likewise, it might be difficult to maintain ideal relative humidity. However, it is important to consider temperature and relative humidity together, as high humidity is likely to be more problematic at the extremes of temperature.

103. Environmental factors should be assessed and recorded as appropriate to the system subject to veterinary or technical advice, in particular when it is clear that environmental factors or the pigs’ behaviour has changed. Measurements should be made at locations that are relevant to the conditions experienced by the pigs.

104. Temperature and air quality can be controlled by a combination of an efficient ventilation system, adequate insulation to the roof, walls and floors of the building, and heating where appropriate. The ventilation rate should always be sufficient to maintain suitable air quality.

105. Ventilation equipment should be kept clean, dust free and well maintained, and operated according to the manufacturer’s recommendations.

106. The farm’s health and welfare plan should detail any additional protocols or management changes needed at different times of the year to help the pigs cope with fluctuating external temperatures, taking into account liveweight; age; group size; herd health; floor type (presence or absence of bedding); air speed and humidity.

107. Pigs are highly susceptible to heat stress. There should be some dry lying area available as a matter of choice, so that the pigs can move away to cooler conditions. There should be contingency plans for lengthy spells of hot weather or where building temperatures are likely to become elevated. Where necessary, and during the summer months, these could include reducing the stocking density; using water sprays; providing shade and wallowing areas; or misting incoming air. Air flow can be increased, for example by opening drop out windows and vents or altering side curtains, where such action would not compromise controlled ventilation systems, including in relation to humidity control.

108. Cold stress can also be harmful to pigs, especially the very young in all systems and all pigs kept in systems lacking active control of the environment. Provision of supplemental heating, increased insulation and bedding, minimising draughts over pigs and any other actions may be essential to minimise harm in cold weather. These should also be included in contingency plans as appropriate.

109. The contingency plan should also include mitigations for wide fluctuations in daily external temperatures to avoid stress which may lead to disease or behavioural problems. (See paragraphs 22 to 26 for further guidance relating to contingency planning.)

110. Deep straw bedding can help create a microclimate to moderate temperature changes. However, both too much and too little straw, particularly in outdoor farrowing accommodation, can lead to increases in piglet mortality.

111. When pigs are moved to new accommodation, the pen should be dry and at a similar temperature to that from which the pig has been moved. This is particularly important for newly weaned pigs.

112. When removing slurry from under slats, special care should be taken to avoid a concentration of dangerous gases, which are a danger to both humans and pigs. Ideally, the building should be empty or very well ventilated during the procedure.

113. Paragraphs 207 onwards provide more specific guidance in relation to outdoor pigs.

Lighting and noise levels

Paragraph 16 of schedule 1 of the Welfare of Farmed Animals (Scotland) Regulations 2010 states that:

16. Animals kept in buildings must not be kept without an appropriate period of rest from artificial lighting.

Paragraphs 7 and 18 of schedule 6 of the Welfare of Farmed Animals (Scotland) Regulations 2010 state that:

7. Where pigs are kept in an artificially lit building then lighting with an intensity of at least 40 lux must be provided for a minimum period of 8 hours per day, subject to paragraph 16 of Schedule 1.

18.—(1) Pigs must not be exposed to constant or sudden noise.

(2) Noise levels above 85 dBA must be avoided in that part of any building where pigs are kept.

114. Owners / keepers should routinely check light intensities are appropriate and keep a record of intensities in pens at all stages of rearing, including farrowing accommodation. It is permissible for some parts of the building to have a light intensity of less than 40 lux, as long as the main, brighter, area is large enough for all the pigs to be in at once if they choose. Providing areas of the pen with different light intensities to enable pigs to choose their preferred lighting can help to enhance welfare. Lighting should be regularly checked, maintained and cleaned.

115. Pigs must not be exposed to constant or sudden noise. However, the use of radios (or similar) can help pigs to become acclimatised to some noise levels and make them less likely to be startled by unexpected noises. The siting of machinery such as feed milling units should be appropriate to minimise the noise impact on pigs.

Automated and mechanical equipment

Paragraphs 18 – 21 of schedule 1 of the Welfare of Farmed Animals (Scotland) Regulations 2010 state that:

18. All automated or mechanical equipment essential for the health and well-being of the animals must be inspected at least once a day to check that there is no defect in it.

19. Where any defect in automated or mechanical equipment of the type specified in paragraph 18 is discovered, it must be rectified immediately, or if that is impossible, appropriate steps must be taken to safeguard the health and well-being of the animals pending the rectification of such defects including the use of alternative methods of feeding and watering and methods of providing and maintaining a satisfactory environment.

20. Where the health and well-being of animals is dependent on an artificial ventilation system—

(a) provision must be made for an appropriate back-up system to guarantee sufficient air renewal to preserve the health and well-being of the animals in the event of failure of the system; and

(b) an alarm system (which will operate even if the principal electricity supply to it has failed) must be provided to give warning of any failure of the system.

21. The back-up system referred to in paragraph 20(a) must be thoroughly inspected, and the alarm system referred to in paragraph 20(b) tested, in each case not less than once every 7 days in order to check that there is no defect in it, and, if any defect is found in such system or alarm (whether or not on it being inspected or tested in accordance with this paragraph), it must be rectified forthwith.

116. All equipment, including feed hoppers, drinkers, ventilation equipment, heating and lighting units, fire extinguishers, and alarm systems, should be cleaned and inspected regularly and kept in good working order. All mains electrical equipment should meet relevant standards and be properly earthed, safeguarded from rodents and out of the pigs’ reach.

117. Any health and welfare plan should include contingency plans for anticipated risks to key animal welfare needs caused by failure of any automated system. If, for example, water supply relies on a pressurised supply that fails and it is unable to be fixed, there should be a plan in place for providing an alternative water supply to all pigs to meet their daily needs, including over the weekend.

Feed, water and other substances

Paragraphs 22 to 27 of schedule 1 of the Welfare of Farmed Animals (Scotland) Regulations 2010 state that:

22. Animals must be fed a wholesome diet which is appropriate to their age and species and which is fed to them in sufficient quantity to maintain them in good health, to satisfy their nutritional needs and to promote a positive state of well-being.

23. Animals must not be provided with food or liquid in a manner, nor must such food or liquid contain any substance, which may cause them unnecessary suffering or injury.

24. All animals must have access to feed at intervals appropriate to their physiological needs (and, in any case, at least once a day), except where a veterinary surgeon acting in the exercise of that profession otherwise directs.

25. All animals must either have access to a suitable water supply and be provided with an adequate supply of fresh drinking water each day or be able to satisfy their fluid intake needs by other means.

26. Feeding and watering equipment must be designed, constructed, placed and maintained so that contamination of food and water and the harmful effects of competition between animals are minimised.

27.(1) No other substance, with the exception of those given for therapeutic or prophylactic purposes or for the purpose of zootechnical treatment, may be administered to animals unless it has been demonstrated by scientific studies of animal welfare or established experience that the effect of that substance is not detrimental to the health or welfare of the animals.

(2) In this paragraph “zootechnical treatment” means the administering to any animal, after examination by (or supervised by) a veterinarian, of any substance authorised by the Scottish Ministers for synchronising oestrus and preparing donors and recipients for the implantation of embryos.

Paragraph 14 of schedule 6 of the Welfare of Farmed Animals (Scotland) Regulations 2010 states that:

14.—(1) All pigs must be fed at least once a day.

(2) Where pigs are housed in a group and do not have continuous access to feed, or are not fed by an automatic feeding system for feeding the animals individually, each pig must have access to the food at the same time as the others in the feeding group.

118. It is illegal to feed any catering waste, kitchen scraps, meat or meat products to farmed animals, including pigs. The ban includes using kitchen waste from all households and any catering waste from any establishment regardless of whether they are vegan or vegetarian kitchens.

119. All pigs need a balanced daily diet to maintain full health and vigour, and any changes in diet should be planned and introduced gradually. The nature of the diet and the way in which it is delivered to the pigs has an impact on their overall welfare. For example, increasing the roughage content and increasing the time taken to eat (e.g. by scattering a proportion of the feed rather than providing in troughs) can help to reduce hunger in restrict-fed animals and stimulate natural foraging behaviour respectively.

120. When introducing pigs to unaccustomed housing or, for outdoor systems, a new paddock, owners / keepers should make sure that the animals are able to find the feed and water points. When newly weaned piglets are moved to pens where water is provided through nipple drinkers unfamiliar to the piglets, it is good practice to provide alternative water sources for the first few days.

121. Where pigs are not fed ad-lib, and where they are fed as a group, and food delivery is intermittent or rationed, owners / keepers must ensure that adequate trough or feeder space is provided to ensure that all pigs can feed at the same time without interference from other pigs. The following guidelines for trough space per pig apply:

Weight of pig (kg) Trough space(cms)
5 10
10 13
15 15
35 20
60 23
90 28
120 30

122. Good hygiene is necessary for storage and feeding systems, as moulds can develop in stale feed which is harmful to pigs.

Paragraph 15 of schedule 6 of the Welfare of Farmed Animals (Scotland) Regulations 2010 states that:

15. All pigs over 2 weeks of age must have permanent access to a sufficient quantity of fresh drinking water.

123. There are various factors which should be taken into consideration when looking at the provision of water to pigs:

a) the total volume available;

b) the flow rate (pigs will not spend a long time taking water);

c) the method of provision, for example, the type of drinker;

d) its accessibility to all pigs over two weeks of age, including sick and injured pigs in the hospital pens;

e) the requirement for increased water supply for consumption during hot weather and for sick pigs, for example with diarrhoea;

f) water supplies to meet other needs, for example for cooling down in pens and for wallows on outdoor units;

g) its suitability as a safe drinking water source (and appropriate regular testing requirements) if the water is not a mains water supply;

h) the need for water delivery systems to be kept hygienic; and

i) the daily routine of owners / keepers to check on water supplies to all pigs to comply with legal requirements.

124. The following is a guide to minimum daily water requirements for various weights of pig:

Weight of pig (kg) Daily requirement (litres) Minimum flow rate through nipple drinkers (litres/min)
Newly weaned 1.0 – 1.5 0.3
Up to 20 kg 1.5 – 2.0 0.5 – 1.0
20 kg – 40 kg 2.0 – 5.0 1.0 – 1.5
Finishing pigs up to 100 kg 5.0 – 6.0 1.0 – 1.5
Sows and gilts – pre-service and in-pig 5.0 – 8.0 2.0
Sows and gilts - in lactation 15 – 30 2.0
Boars 5.0 – 8.0 2.0

125. Waste water and excessive or insufficient flow rates can be detrimental, particularly for sows in farrowing accommodation and very young pigs. The water supply connected to a wet-dry feeder should not be counted as a sufficient water supply alone for drinking, since feeding pigs will block access to these points.

126. The height at which water nipples and bowls are placed should be carefully considered. All pigs should be able to access the drinking point so this might require it to be height-adjustable, or there may have to be several different drinkers at various heights when groups of pigs, of a range of weights, are housed together or when pigs are housed in a pen for a long period.

127. Where nipple drinkers are used, a drinking point should be available for every ten weaner pigs and any other pigs on rationed feeding. On unrestricted feeding, one nipple drinker should provide adequate supply for 15 pigs given sufficient flow rates. Bowl drinkers which have a reservoir of water contained within them, should be suitable to supply 30 pigs per bowl. Where trough systems are used, the following guidelines should be applied:

Weight of pig (kg) Trough space per head (cm)
Up to 15 0.8
15 - 35 1.0
>35 1.2

128. Pigs are highly susceptible to dehydration and the condition commonly known as “salt poisoning”. In an emergency, where access to sufficient water is likely to be limited for 24 hours or more, an alternative system of manually supplying water must be provided. Water must not be withdrawn from sows which are being dried off at weaning. Water must also continue to be provided for any pigs prior to slaughter.


Email: animal_health_welfare@gov.scot

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