Pig farms

Pig farms

Today most pigs are raised in factory farms, which are sometimes called “hog lots”. In the USA and Europe this method of rearing pigs has prevailed for decades. But recently pig farming has also grown significantly in China, where it is estimated that approximately half of the pigs that are killed in the world are slaughtered.1

To produce the quantities of pig meat needed to meet customer demand, contemporary farming focuses on raising pigs as quickly as possible while occupying the least possible space. The result of this is that the pigs’ lives consist of continuous suffering due to the way they are forced to live. We will now look at why.

There is a difference between closed cycle pig farms (where the complete exploitation process is carried out in the same industrial unit), and those where reproduction, transition and final growth (the ‘finishing’, as farmers call it) are carried out in different places, between which animals must be transported when one stage of their exploitation ends and another begins.

There are several different facilities for the different stages in pig breeding, which are described below.


Female pigs used for reproduction are kept locked in crates during gestation, which lasts about 114 days (around 16 weeks). These crates are individual, made of metal, and usually have floors made of railings. Gestation areas can have two zones: one called the ‘mating area’, where sows and gilts are impregnated, commonly by artificial insemination, and one where sows or mated gilts, once pregnant, spend the rest of the gestation period until around a week before giving birth. The semen is usually purchased from pig genetics companies that keep selected boars to obtain their semen, usually by using a ‘dummy sow’.

These individual stalls are extremely narrow and barely bigger than the animals themselves. Therefore the pigs are not only deprived of any exercise, but they can hardly move. They cannot turn around, and it is even difficult for them to change their position from lying down to standing up and vice versa. They can only move forwards and backwards, and their ability to do even that is limited. So there is literally nothing that these animals can do. Their total lack of space is also damaging to their muscles, joints and bones, and in general for their health. They can suffer from conditions such as lameness and cardiovascular problems. In addition, because the crates are so narrow and tight, they often suffer from injuries as a result of the abrasion of their skin against the metal of the crates. They are also deprived of social contact. Most sows are currently kept this way during their pregnancy. As we will see below, this can cause them extreme boredom and significant distress.2

Gestation stalls are currently being phased out by law in the European Union, but they are commonly used all around the world.

In other cases, sows are kept in groups. In groups they do not suffer as much from boredom and lack of social interaction, and it is possible for them to move around a bit more. Nevertheless the situation in these cases is still one of much suffering and frustration for the pigs, due to the crowded, unstimulating environment in which they can’t engage in many of their natural activities. It is often unsanitary as well. As a result, situations where the pigs attack one another are relatively common. This happens in particular over food, and means that animals can be injured and suffer from stress. In addition, it may mean some animals do not get adequate food and subsequently suffer from hunger.3


Shortly before giving birth, sows are moved from gestation stalls to farrowing crates, in which they give birth. There are some farms where this does not happen, and where piglets are born in small outdoor pens called farrowing arcs.4 But in most cases birth takes place in farrowing crates similar to the ones where the sows were kept previously, except that they have room alongside the sows for the piglets. When they are moved from one crate to another, violence is often used because the animals refuse to go back into a prison just as terrible as the ones they were in before.

In the farrowing crates the sows have so little room that they can accidentally crush their piglets.5 To prevent this, the farrowing crates are designed so that sows cannot move and turn around in them. They are basically like sow stalls in that the sows can only move enough to stand up and lie down, and even this is with difficulty. The floor is comprised completely of rails, except for a small area where the piglets are. The piglets will live in this area until they are weaned. This happens around 21-25 days later. If this weren’t done, piglets would normally spend several months with their mothers. Then the piglets are carried out to the transition area.

The sows are moved back to the mating area, where they are impregnated again. On average, sows can give birth more than twice a year. For them this is a cycle that only ends when they are finally sent to the slaughterhouse.6 This usually happens when they are around three years old. However, they could reach the age of 15 or older if their lives were respected (their lifespans are similar to those of dogs).

Transition to the “finishing” area

Once they are weaned, the piglets are carried out to a transition area where they gain weight before they are finally brought to the finishing area, at around 70 days old.


Piglets are then taken to the so-called “finishing” area, where they stay until their weight is heavy enough for them to be taken to the slaughterhouse. The overwhelming majority of these animals spend the rest of their lives indoors, without even seeing sunlight (even those who were born in farrowing arcs outdoors). Some of them have some access to straw, while others do not because the farm cleaning systems do not allow for it. Finally, they are killed when they are less than four months old if they are meant for the production of suckling pig meat, or when they are around seven months old if they are meant for the production of standard pig meat.

A filthy place to live

Throughout all the breeding stages, the animals’ excrement is piled in holes below the railings of their cages. There are occasions on which these holes are not deep enough to contain all the feces, so it eventually spreads into the crates where the animals are.

There is a myth that pigs are very dirty animals, which is probably due to the fact that, being unable to sweat, they take mud baths to refresh themselves, and also because humans have traditionally kept them in very dirty conditions. The truth is that these animals are much cleaner than this myth assumes, and certainly dislike having to live in their own excrement. However, that is the situation in which they find themselves on farms, and they have to endure the terrible stench. The ventilation is not enough to make a difference and refresh the air. As a result, many of these animals suffer from respiratory conditions.

Pigs’ physical and mental health

It is also easy for diseases to spread among pigs. The situation they endure and the poor food they are given result in poor health conditions, and they often suffer from digestive and urinary tract problems. Even though they are given antibiotics, every now and then they suffer from pandemics such as swine flu and foot and mouth disease, among others.

In the case of pandemics, animals are commonly slaughtered en masse. In normal situations, sick animals are also routinely killed when they become ill, rather than being treated. Piglets are killed simply by slamming their tiny heads against the wall, floor or metal bars. In many cases farmers do not even bother to kill them but simply move them away from the areas where they are fed and just abandon them to die in agony. Pigs who suffer accidents are also often left to die. A researcher looking into the ways animals die in slaughterhouses and farms investigated the pig industry and wrote the following:

Sick and injured pigs were routinely dragged into narrow alleyways between pens where they were provided with no food or water and were left to die slowly of disease, starvation, and dehydration. “How long will these sick and injured pigs lie there without food and water?” we asked. “A week. Depends on how long it takes them to die. Two weeks,” said a worker. Those pigs that were “euthanized” were frequently beaten to death with hammers and gate rods. “I’ve seen people just take a straight hammer and start wailing on them. I’ve seen pigs with their whole head crushed in get thrown into the dead box and three days later they will still be breathing,” said one worker. “Or you stand on their neck. The way to do it now, we take the water hose and stick in down their throat and blow them up, and their butt-holes pop out. We just drown them to death.” Thousands of piglets whose legs became trapped between floor slats were simply abandoned to die of starvation or dehydration. Weanling piglets that got too close to heat lamps were left to burn to death. “We call them ‘baby back ribs’ and ‘crispy critters,’” the workers told us.7

Many others are not killed, but live their whole lives with wounds, ulcers or injuries, which may include broken bones, left completely unattended, which leaves them in constant pain.

Pigs’ tolerance to high temperatures is very limited; if it’s very hot they can suffer from heat stress and many can die as a result. Since they don’t have access to water or mud to refresh themselves, there’s no way they can avoid this.

In addition, their mental health is also severely affected by their situation. They not only lack space and are unable to go out, they also lack anything that could make their lives more comfortable, such as straw or other materials to build a nest. There is also nothing interesting for them to do or for them to examine on the farms. Since pigs are very curious, this contributes to their suffering. As a result, they commonly display behavior such as biting the bars of the farrowing crates, which shows their frustration, boredom and depression.8

Painful mutilations

This distressing situation drives piglets to display abnormal behavior and to bite each other’s tails. In addition, they can also bite their mothers’ breasts while they are feeding, without their mother being able to push them away or move to avoid this, because they are completely immobilized in the farrowing crates. To prevent this from happening, piglets’ teeth and tails are clipped, a procedure that causes them very severe pain. In addition, the males are castrated. All this is done without any anesthetic or painkillers, which causes them horrendous suffering.9 Their ears are also mutilated to brand them, which is extremely painful.

The end of their lives

The way to stop all this suffering of these animals is to stop the demand for the products that are obtained as a result of their exploitation. Some people might think that free range farming may be a solution to stop all this abuse to pigs from occurring. But it is important to remember that even if some of the abuses suffered by pigs on factory farms does not take place on these extensive farms, they are still greatly harmed; pigs are sent to slaughterhouses in trucks where they suffer terribly (as explained in Transport to death). At slaughterhouses they are subjected to electro narcosis (where an electrical discharge is applied to their head with electric pliers), or the gas chamber, and shackled upside down and slit open with a knife so that they bleed to death. They are therefore painfully deprived of their lives at a very young age.

Further readings

Andresen, N. & Redbo, I. (1999) “Foraging behaviour of growing pigs on grassland in relation to stocking rate and feed crude protein level”, Applied Animal Behaviour Science, 62, pp. 183-197.

Arey, D. S. (1993) “The effect of bedding on the behaviour and welfare of pigs”, Animal Welfare, 2, pp. 235-246.

Barnett, J. L.; Hemsworth, P. H.; Cronin, G. M.; Jongman, E. C. & Hutson, G. D. (2001) “A review of the welfare issues for sows and piglets in relation to housing”, Australian Journal of Agricultural Research, 52, pp. 1-28.

Braund, J. P.; Edwards, S. A.; Riddoch, I. & Buckner, L. J. (1998) “Modification of foraging behaviour and pasture damage by dietary manipulation in outdoor sows”, Applied Animal Behaviour Science, 56, pp. 173-186.

Brent, G. (1986) Pig housing, Ipswich: Farming Press.

Connor, M. L. (1993) “Evaluation of biotech housing for feeder pigs”, Manitoba Swine Update, 5, pp. 1-2.

Den Ouden, M.; Nijsing, J.; Dijkhuizen, A. & Huirne, R. (1997) “Economic optimization of pork production-marketing chains: I. Model input on animal welfare costs”, Livestock Production Science, 48, pp. 23-37.

Edwards, S. A. & Fraser, D. (1997) “Housing systems for farrowing and lactation”, Pig Journal, 37, pp. 77-89.

European Commission (1997) “The welfare of intensively kept pigs”, Report of the Scientific Veterinary Committee, 30 September [accessed on 3 May 2013].

Fraser, D. (1984) “The role of behaviour in swine production: A review of research”, Applied Animal Ethology, 11, pp. 317-339.

Gjein, H. & Larssen, R. B. (1995) “Housing of pregnant sows in loose and confined systems – a field study. 1. Vulva and body lesions, culling reasons, and production results”, Acta Veterinaria Scandinavia, 36, pp. 185-200.

Harmon, J. D. & Lawrence, J. (1995) Open vs. enclosed swine finishing: Making the decision, Ames: Iowa State University.

Hemsworth, P. H. & Coleman, G. J. (1998) Human-livestock interactions: The stockperson and the productivity and welfare of intensively farmed animals, Wallingford: CAB International.

Honeyman, M. S. & Harmon, J. D. (2003) “Performance of finishing pigs in hoop structures and confinement during winter and summer”, Journal of Animal Science, 81, pp. 1663-1670.

Jonge, F. H.; de Bokkers, E. A. M.; Schouten, W. G. P. & Helmond, F. A. (1996) “Rearing piglets in a poor environment: Developmental aspects of social stress in pigs”, Physiology & Behavior, 60, pp. 389-396.

Martins, A. & Day, J. (2002) Optimising production systems for organic pig production (OF0169), King’s Lynn: ADAS Terrington [accessed on 12 April 2013]

Rauw, W. M.; Kanis, E.; Noordhuizen-Stassen, E. N. & Grommers, F. J. (1998) “Undesirable side effects of selection for high production efficiency in farm animals: A review”, Livestock Production Science, 56, pp. 15-33.

Sainsbury, D. (1986) Farm animal welfare. Cattle, pigs and poultry, London: Collins.

Schneider, M. & Sharma, S. (2014) “China’s pork miracle?: Agribusiness and development in China’s pork industry”, Institute for Agriculture and Trade Policy, February [accessed on 24 December 2016].

Schrøder-Petersen, D. L. & Simonsen, H. B. (2001) “Tail biting in pigs”, The Veterinary Journal, 162, pp. 196-210.

St. Pierre, N. R.; Cobanov, B. & Schnitkey, G. (2003) “Economic losses from heat stress by US livestock industries”, Journal of Dairy Science, 86, pp. E52-E77.

Thornton, K. (1990) Outdoor pig production, Ipswich: Farming Press.

Tubbs, R. C.; Hurd, H. S.; Dargatz, D. & Hill, G. (1993) “Preweaning morbidity and mortality in the United States swine herd”, Journal of Swine Health and Production, 1, pp. 21-28 [accessed on 14 July 2013].

Vaarst, M.; Roepstorff, A.; Feenstra, A.; Hogedal, P.; Larsen, V. A.; Lauritsen, H .B. & Hermansen, J. E. (1999) “Animal health and welfare aspects of organic pig production”, in Alföldi, T.; Lockeretz, W. & Niggli, U. (eds.) Proceedings of the 13th International IFOAM Scientific Conference, 28-31 August 2000, Basel: VDF Hochschulverlag an der Eidgenössische Technische Hochschule Zürich, p. 373.

Vaillancourt, J. P. & Tubbs, R. C. (1992) “Preweaning mortality”, The Veterinary clinics of North America. Food Animal Practice, 8, pp. 685-706.

Weber, R. & Zarate, A.V. (2000) Welfare of fattening pigs in different husbandry systems, Wageningen: Wageningen Academic.


1 Food and Agriculture Organization of the United Nations (2020) “Livestock primary”, FAOSTAT [accessed on 4 January 2020].

2 Rushen, J. & Passillé, A. M. B. D. (1992) “The scientific assessment of the impact of housing on animal welfare: A critical review”, Canadian Journal of Animal Science, 72, pp. 721-743. Wemelsfelder, F. (2005) “Animal boredom: Understanding the tedium of confined lives”, in McMillan, F. (ed.) Mental health and well-being in animals, Oxford: Blackwell, pp. 77-91. Candiani, D.; Salamano, G.; Mellia, E.; Doglione, L.; Bruno, R.; Toussaint, M. & Gruys, E. (2008) “A combination of behavioral and physiological indicators for assessing pig welfare on the farm”, Journal of Applied Animal Welfare Science, 11, pp. 1-13. Wemelsfelder, F.; Hunter, A. E.; Paul, E. S. & Lawrence, A. B. (2012) “Assessing pig body language: Agreement and consistency between pig farmers, veterinarians, and animal activists”, Journal of Animal Science, 90, pp. 3652-3665.

3 See for instance regarding sow stalls and farrowing crates: Anil, L.; Anil, S. S. & Deen, J. (2002) “Relationship between postural behaviour and gestation stall dimensions in relation to sow size”, Applied Animal Behaviour Science, 77, p. 173. Bracke, M. B. M.; Metz, J. H. M.; Spruijt, B. M. & Dijkhuizen, A. A. (1999) “Overall welfare assessment of pregnant sow housing systems based on interviews with experts”, Netherlands Journal of Agricultural Science, 47, pp. 93-104. Marchant, J. N. & Broom, D. M. (1996) “Effects of dry sow housing conditions on muscle weight and bone strength”, Animal Science, 62, pp. 105-113. McGlone, J. J.; Vines, B.; Rudine, A. C. & DuBois, P. (2004) “The physical size of gestating sows”, Journal of Animal Science, 82, pp. 2421-2427. Salak-Johnson, J. L.; Niekamp, S. R.; Rodriguez-Zas, S. L.; Ellis, M. & Curtis, S. E. (2007) “Space allowance for dry, pregnant sows in pens: Body condition, skin lesions, and performance”, Journal of Animal Science, 85, pp. 1758-1769.

4 Edwards, S. A.; Smith, W. J.; Fordyce, C. & MacMenemy, F. (1994) “An analysis of the causes of piglet mortality in a breeding herd kept outdoors”, Veterinary Record, 135, pp. 324-327.

5 Marchant, J. N.; Rudd, A. R.; Mendl, M. T.; Broom, D. M.; Meredith, M. J.; Corning, S. & Simmins, P. H. (2000) “Timing and causes of piglet mortality in alternative and conventional farrowing systems”, Veterinary Record, 147, pp. 209-214.

6 Dagorn, J. & Aumaitre, A. (1979) “Sow culling; reasons for and effect on productivity”, Livestock Production Science, 6, pp. 167-177.

7 Eisnitz, G. (1997) Slaughterhouse: The shocking story of greed, neglect, and inhumane treatment inside the U.S. meat industry, Amherst: Prometheus.

8 Blackshaw, J. K., & McVeigh, J. F. (1985) “Stereotype behaviour in sows and gilts housed in stalls, tethers, and groups”, in Fox, M. W. & Mickley, L. D. Advances in Animal Welfare Science 1984, Dordrecht: Springer, pp. 163-174. Lawrence, A. B. & Terlouw, E. (1993) “A review of behavioral factors involved in the development and continued performance of stereotypic behaviors in pigs”, Journal of Animal Science, 71, pp. 2815-2825. Cronin, G. M.; Smith, J. A.; Hodge, F. M. & Hemsworth, P. H. (1994) “The behaviour of primiparous sows around farrowing in response to restraint and straw bedding”, Applied Animal Behaviour Science, 39, pp. 269-280. McGlone, J. J.; Borell, E. H. von; Deen, J.; Johnson, A. K.; Levis, D. G.; Meunier-Salaün, M.; Morrow, J.; Reeves, D.; Salak-Johnson, J. L. & Sundberg, P. L. (2004) “Review: Compilation of the scientific literature comparing housing systems for gestating sows and gilts using measures of physiology, behavior, performance, and health”, The Professional Animal Scientist, 20, 105-117.

9 Brown, J. M. E.; Edwards, S. A.; Smith, W. J.; Thompson, E. & Duncan, J. (1996) “Welfare and production implications of teeth clipping and iron injection of piglets in outdoor systems in Scotland”, Preventive Veterinary Medicine, 27, pp. 95-105. White, R. C.; DeShazer, J. A.; Tressler, C. J.; Borches, G. M.; Davey, S.; Waninge A.; Parkhust, A. M.; Milanuk, M. J. & Clems, E. I. (1995) “Vocalization and physiological response of pigs during castration with and without anesthetic”, Journal of Animal Science, 73, pp. 381-386. McGlone, J. J.; Nicholson, R. I.; Hellman, J. M. & Herzog, D. N. (1993) “The development of pain in young pigs associated with castration and attempts to prevent castration induced behavioral changes”, Journal of Animal Science, 71, pp. 1441-1446.