In November 2024, the Centre National National de Référence pour le Bien-Etre Animal (CNR BEA) published a literature review on the impacts of different soiling types (solid floor, partly slatted floor, or fully slatted floor) on the welfare and behavior of pigs. Here is a summary of this work.
In France, the vast majority of pig farming takes place indoors. The flooring used in these buildings can vary depending on the type of farming or the stage of rearing (farrowing, post-weaning, finishing). Each type of flooring has its advantages and disadvantages, both economically and in terms of animal and human welfare. Regarding pig welfare, particular attention is paid to the impact of flooring on hygiene, health, and behavioral expression.
Keep in mind
- The majority of pig farms in France use fully slatted floors (solid slats alternating with openings).
- The type of flooring and the presence of bedding will influence the behavior of pigs.
- The welfare of pigs increases according to the type of flooring, following a gradient (fully slatted flooring < partly slatted flooring < solid flooring < deep litter), which is associated with the amount of straw provided.
Pig behavior
Pig behavior
Indoor pigs spend most of their time lying down and feeding. While very common when pigs are kept in semi-free ranges, interactions with their environment (particularly exploration, oral manipulation, and foraging behaviors) are often limited by the type of flooring used.
Here are some examples of the main behavioral categories in pigs:
Elimination (defecation and urination)
Rest
Comfort behavior
Feeding
Thermoregulation
Nesting
Social interactions
Manipulation, investigation, exploration
📌 Examples of materials that pigs can handle:
- Materials used for bedding: straw, sawdust/wood shavings, peat
- Nesting materials: bedding, long-stem straw, chopped straw, alfalfa hay, hay, burlap
- Feed-type materials: bread, hay/fodder
- Deformable objects: rubber hoses, wooden sticks, ropes, burlap sacks
- Non-deformable objects: balls, plastic balloons or metal chains
If pigs cannot express these behaviors, it can generate frustration and be a source of distress, but also induce redirected behaviors, including tail biting.
Redirected behaviors
Did you know?
According to the EFSA, tail biting is "inflicted by conspecifics, and results in damage to the skin, muscles, bones, cartilage, blood vessels and nerve tissue"[1]. This abnormal behavior is multifactorial, with risk factors such as a lack of enrichment or the percentage of slatted flooring. Prevention currently most often involves tail docking, a painful procedure that does not address the underlying causes of tail biting. Although European legislation prohibits this procedure as a routine practice, it remains widely used in France, based on exemptions.
Advantages and disadvantages of soil types for pigs and farmers
Fully slatted flooring
A fully slatted floor is a floor entirely composed of solid slats alternating with openings that allow for the removal of manure. It is made from various materials such as concrete, metal or plastic, which are generally selected according to the production stage (farrowing, birth, post-weaning, finishing).
This type of flooring is mainly used in pig farming in Europe and in France. In 2018, it was estimated that it represented approximately 85 to 90% of French livestock buildings.
Advantages and disadvantages for pigs
Benefits identified by the CNR BEA
Good manure removal: the enclosure and animals are cleaner.
Good animal and environmental hygiene: reduced risk of infectious diseases caused in particular by salmonella.
Favorable for thermoregulation in pigs during hot weather because it is cooler than other types of flooring.
Disadvantages identified by the CNR BEA
In winter, it makes pigs’ thermoregulation less effective and can lead to heat stress.
The lack of enrichment in this type of enclosure, often combined with high animal density, poses a high risk of redirected behaviors toward conspecifics, including tail biting.
Enrichment materials (e.g., litter and fodder) that allow for exploratory and nesting behaviors are mostly incompatible with this type of flooring because they can get stuck in the openings and block the manure removal.
Increases the risk of foot injuries, lameness, tail and ear wounds, and bursitis (inflammation around the joints).
Ammonia emissions from the pre-pit (the pit beneath the animals where waste falls) can also lead to poor air quality and cause respiratory and eye problems for pigs and humans. High concentrations of ammonia in the air are among the risk factors for tail biting.
Advantages and disadvantages for breeders
Benefits identified by the CNR BEA
Low costs related to adding substrates or labor for cleaning and waste management.
Possibility to valorize the collected slurry.
Disadvantages identified by the CNR BEA
Tail biting leads to economic losses due to carcass downgrading at the slaughterhouse (the carcass is reclassified into a lower quality category) and requires more interventions on the animals.
Ammonia emissions from the slurry pit pollute the environment and can cause nuisance for nearby residents.
Partly slatted flooring
Partly slatted flooring combines a slatted section (30 to 50% of the surface area) with a solid floor area, known as lying area. The solid floor is often made of concrete, sometimes with bedding. Pigs prefer to lie down in the lying area, while the slatted section is used for waste disposal.
This type of flooring aims to balance hygiene and comfort: the slatted section keeps the enclosure clean, while the solid floor offers a more comfortable resting space.
In 2015 in France, it was estimated that partly slatted flooring was present in 9% of livestock buildings.
Advantages and disadvantages for pigs
Benefits identified by the CNR BEA
The solid section offers pigs more comfort than slatted flooring when they are lying down.
The animal can divide the space into several living areas (sleeping area, elimination area): this helps keep the sleeping area clean.
Favors thermoregulation in pigs, which can lie on slatted flooring during hot periods and on solid flooring during cold periods.
Causes less foot lesions and lameness than solid flooring.
Disadvantages identified by the CNR BEA
If stocking density and/or temperature are too high, pigs will defecate on the solid-floor area (fouling), which harms the hygiene of both the animals and the pen.
Fouling disrupts pigs’ resting behavior and increases negative interactions between them.
Without rooting materials and without added straw, pigs have few opportunities to express exploratory and nest-building behaviors, increasing the risk of tail biting.
Partially slatted flooring increases the occurrence of leg injuries compared with fully solid flooring.
The effects of partially slatted floors on ammonia emissions are still debated.
Advantages and disadvantages for breeders
Benefits identified by the CNR BEA
Low costs related to adding substrates or labor for cleaning and waste management.
Odor emissions are less intense than with fully slatted floor.
Disadvantages identified by the CNR BEA
Same disadvantages as fully slatted floor.
Solid flooring
A solid floor is a non-perforated surface, often made of concrete, where excrement needs to be removed regularly, either manually or with mechanical scrapers; urine is often drained separately.
This type of flooring can be used with no bedding, with a thin layer of straw, or with deep litter ( > 10 – 15 cm of straw or sawdust).
In 2015, approximately 5% of French pig buildings used deep litter, while less than 0.5% used solid flooring with no bedding or with scraped litter.
Solid flooring with no bedding
Advantages and disadvantages for pigs
Benefits identified by the CNR BEA
Greater comfort when resting than on slatted floors.
Negative social interactions between pigs are less common than on slatted floors.
Pigs have fewer foot injuries and lameness than on slatted floors.
Disadvantages identified by the CNR BEA
With insufficient cleaning, manure can accumulate and affect pig hygiene.
Maintaining floor hygiene is more difficult, increasing the risk of gastroenteritis.
On slippery floors (due to excrement, for instance) pigs are more likely to slip, fall, and injure themselves.
Concrete floors that are in poor condition or too abrasive cause greater damage to the feet.
Advantages and disadvantages for breeders
Benefits identified by the CNR BEA
Lower energy costs than with full or partially slatted floors.
Disadvantages identified by the CNR BEA
More cleaning work than with slatted floors.
Solid flooring with scraped litter
Advantages and disadvantages for pigs
Benefits identified by the CNR BEA
Good separation of living areas: with the straw-covered resting area, reduced risk of fouling.
Better thermal comfort: pigs prefer to lie on straw when temperatures are low or neutral and on solid flooring when temperatures are high.
Better expression of exploration and nesting behaviors than on solid flooring with no bedding, depending on the amount of straw provided: the risk of tail biting is greatly reduced.
Negative social interactions are less prevalent than on slatted flooring.
Better grip on the floor compared to slatted floors and solid floors with no bedding, reducing the risk of falls.
Less ammonia emissions than solid flooring with no bedding thanks to absorption by litter.
Disadvantages identified by the CNR BEA
If too little straw is provided: the risk of tail biting and lameness persists.
If the straw is wet: risk of mold growth producing mycotoxins (toxins produced by certain fungi). These risks pose a threat to animal health and may reduce sow fertility.
Advantages and disadvantages for breeders
Benefits identified by the CNR BEA
Fewer carcass downgrades at the slaughterhouse than with slatted floors or solid floors.
Fewer injuries means less animal care.
Possibility of recycling manure.
Lower energy costs compared to slatted floors and solid floors with no bedding.
Ammonia emissions are lower thanks to the bedding, and there is less odor than with fully slatted flooring
Disadvantages identified by the CNR BEA
Cost of straw.
More work for mulching the floor.
Floor hygiene is more difficult to maintain than with slatted floors.
Solid flooring with deep litter
Advantages and disadvantages for pigs
Benefits identified by the CNR BEA
Ensures a clean and dry enclosure.
Deep bedding ensures thermal comfort during cold periods.
Very conducive to exploratory behavior: pigs show increased activity directed toward the litter, such as investigating and rooting.
The thicker the bedding, the more frequent positive social behaviors are and the rarer negative behaviors are, particularly tail biting.
Better nursing behavior in sows and higher piglet survival rates compared to other types of flooring.
Less injuries of carpus and tarsus, no risk of slipping compared to other types of flooring.
More space per animal: the number of pigs per square meter must be lower than in other systems to ensure good hygiene.
Disadvantages identified by the CNR BEA
As temperatures rise, litter fermentation will occur and produce heat, which can lead to pig thermoregulation problems.
Poor-quality straw, wood chips, or sawdust increase the number of airborne particles (e.g., dust, mold, fungi) that are associated with respiratory disorders in pigs and humans.
Compared to scraped litter system, deep litter increases emissions of gases such as ammonia, nitrous oxide, and methane in the building. If litter removal and replacement are not properly managed, deep litter can accumulate viral, bacterial, and parasitic agents.
Advantages and disadvantages for breeders
Benefits identified by the CNR BEA
Fewer carcasses downgraded at the slaughterhouse compared to other flooring types.
Fewer injuries, therefore less animal care required compared to other types of flooring.
Manure can be recycled.
Energy costs are lower compared to other flooring types.
Ammonia emissions are reduced thanks to the bedding.
Disadvantages identified by the CNR BEA
Cost of straw and potential supply issues.
The investment cost is high because the buildings must be specifically designed for this type of soil.
More work for mulching and cleaning at the end of the cycle.
Ammonia and greenhouse gas emissions are still present.
Recommandations of the CNR BEA
Recommandations of the CNR BEA
For each type of soil, the CNR BEA proposes, based on a literature review, a series of recommendations aimed at improving pig welfare. These recommendations do not necessarily imply changing the type of soil used or modifying the building, but rather optimizing conditions to promote animal welfare, regardless of the soil types.
Here are some recommendations that do not require any changes to the building:
- Providing small quantities of bedding, for example chopped straw.
- Distributing several types of objects at once, for manipulation; renewed regularly, and in accordance with Recommendation (EU) 2016/336 [2].
- Installing rubber mats, which should be cleaned regularly.
- Ensuring efficient ventilation of the building.
- Removing the manure regularly.
- Choices for slatted floors:
- plastic /plasticized is preferable for piglets.
- use non-abrasive materials.
- choose slat sizes and openings complying with Directive 2008/120/EC [3] and suitable for the age of the pigs housed.
- Checking regularly for slat condition.
- Distribute several types of objects at once, for manipulation; renewed regularly, and in accordance with Recommendation (EU) 2016/336.
- Installing rubber mats, which should be cleaned regularly.
- Choices for slatted floors:
- plastic /plasticized is preferable for piglets.
- use non-abrasive materials.
- Covering concrete floors with a material that cushions or reduces friction.
- Installing rubber mats, which should be cleaned regularly.
- Regular cleaning of the floor.
Same as solid floor, with the following additions:
- Providing straw in an appropriate quantity for maximum pig exploration.
- Providing at least 20g of straw per pig per day for sleeping comfort and to limit lameness.
- Replacing bedding when soiled.
- Performing maintenance mulching every 7 to 10 days, prioritizing areas of elimination.
- Providing access to a different type of soil during periods of intense heat.
- Anticipating the accumulation of litter at the end of the cycle (+ 40 to 50 cm) by for instance elevating feeding areas.
In conclusion
Alternative flooring to fully slatted floors improves pig welfare by promoting their natural behavior (exploration, nesting), reducing the risk of tail biting and injuries, and offering more comfort and space. Effectiveness increases with the amount of straw, following a gradient from fully slatted floor to deep litter.
Alternative flooring to fully slatted floors requires better management of building ventilation and a larger surface area to ensure the cleanliness of animals and enclosures, thermal comfort in hot weather and reduce the risk of infectious diseases.
Beyond animal welfare, it is important to consider the breeder’s welfare. Floors using bedding require more work and increase the cost of supplies. However, these additional costs can be offset by improved overall health in the pigs, which then require less care and who can be sold a higher price. Buildings with bedding floors may also be more energy-efficient than buildings with other types of flooring.
[1] EFSA Panel on AHAW, 2022. Welfare of pigs on farm. EFSA J. 20, e07421. https://doi.org/10.2903/j.efsa.2022.7421
[2] Recommandation (UE) 2016/336 de la Commission Européenne
Keep in mind
- The majority of pig farms in France use fully slatted floors (solid slats alternating with openings).
- The type of flooring and the presence of bedding will influence the behavior of pigs.
- The welfare of pigs increases according to the type of flooring, following a gradient (fully slatted flooring < party slatted flooring < solid flooring < deep litter), which is associated with the amount of straw provided.
Key Figure
Percentage of pig farming buildings in France with slatted floors.
