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Pig
Domestic pigs
Domesticated
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Suidae
Genus: Sus
Species:
S. domesticus
Binomial name
Sus domesticus
Erxleben, 1777
Synonyms[1]

The pig (Sus domesticus), also called swine (pl.: swine) or hog, is an omnivorous, domesticated, even-toed, hoofed mammal. It is named the domestic pig when distinguishing it from other members of the genus Sus. Some authorities consider it a subspecies of Sus scrofa (the wild boar or Eurasian boar); other authorities consider it a distinct species. Pigs were domesticated in the Neolithic, both in China and in the Near East (around the Tigris Basin). When domesticated pigs arrived in Europe, they extensively interbred with wild boar but retained their domesticated features.

Pigs are farmed primarily for meat, called pork. The animal's skin or hide is used for leather. China is the world's largest pork producer, followed by the European Union and then the United States. Around 1.5 billion pigs are raised each year, producing some 120 million tonnes of meat, often cured as bacon. Some are kept as pets.

Pigs have featured in human culture since Neolithic times, appearing in art and literature for children and adults, and celebrated in cities such as Bologna for their meat products.

Description

[edit]

The pig has a large head, with a long snout strengthened by a special prenasal bone and a disk of cartilage at the tip.[2] The snout is used to dig into the soil to find food and is an acute sense organ. The dental formula of adult pigs is 3.1.4.33.1.4.3, giving a total of 44 teeth. The rear teeth are adapted for crushing. In males, the canine teeth can form tusks, which grow continuously and are sharpened by grinding against each other.[2] There are four hoofed toes on each foot; the two larger central toes bear most of the weight, while the outer two are also used in soft ground.[3] Most pigs have rather sparsely bristled hair on their skin, though there are some woolly-coated breeds such as the Mangalitsa.[4] Adult pigs generally weigh between 140 and 300 kg (310 and 660 lb), though some breeds can exceed this range. Exceptionally, a pig called Big Bill weighed 1,157 kg (2,551 lb) and had a shoulder height of 1.5 m (4 ft 11 in).[5]

Pigs possess both apocrine and eccrine sweat glands, although the latter are limited to the snout.[6] Pigs, like other "hairless" mammals such as elephants, do not use thermal sweat glands in cooling.[7] Pigs are less able than many other mammals to dissipate heat from wet mucous membranes in the mouth by panting. Their thermoneutral zone is 16–22 °C (61–72 °F).[8] At higher temperatures, pigs lose heat by wallowing in mud or water via evaporative cooling, although it has been suggested that wallowing may serve other functions, such as protection from sunburn, ecto-parasite control, and scent-marking.[9] Pigs are among four mammalian species with mutations in the nicotinic acetylcholine receptor that protect against snake venom. Mongooses, honey badgers, hedgehogs, and pigs all have different modifications to the receptor pocket which prevents α-neurotoxin from binding.[10] Pigs have small lungs for their body size, and are thus more susceptible than other domesticated animals to fatal bronchitis and pneumonia.[11] The genome of the pig has been sequenced; it contains about 22,342 protein-coding genes.[12][13][14]

  • Skeleton
    Skeleton
  • Skull
    Skull
  • Bones of the foot
    Bones of the foot

Evolution

[edit]

Phylogeny

[edit]

Domestic pigs are related to other pig species as shown in the cladogram, based on phylogenetic analysis using mitochondrial DNA.[15]

Suidae

Babirusa

Indonesia
Africa

Visayan warty pig

Philippine warty pig

Wild boar

Domestic pig

East Asian pigs

European pigs

Eurasia
Southeast Asia

Taxonomy

[edit]

The pig is most often considered to be a subspecies of the wild boar, which was given the name Sus scrofa by Carl Linnaeus in 1758; following from this, the formal name of the pig is Sus scrofa domesticus.[16][17] However, in 1777, Johann Christian Polycarp Erxleben classified the pig as a separate species from the wild boar. He gave it the name Sus domesticus, still used by some taxonomists.[18] The American Society of Mammalogists considers it a separate species.[19]

Domestication in the Neolithic

[edit]
Further information: Domestication
The initial emergence of wild pigs, followed by the genetic divergence between boars and pigs and the domestication of pigs [20]

Archaeological evidence shows that pigs were domesticated from wild boar in the Near East in or around the Tigris Basin,[21] being managed in a semi-wild state much as they are managed by some modern New Guineans.[22] There were pigs in Cyprus more than 11,400 years ago, introduced from the mainland, implying domestication in the adjacent mainland by then.[23] Pigs were separately domesticated in China, starting some 8,000 years ago.[24][25] In the Near East, pig husbandry spread for the next few millennia. It reduced gradually during the Bronze Age, as rural populations instead focused on commodity-producing livestock, but it was sustained in cities.[26]

Domestication did not involve reproductive isolation with population bottlenecks. Western Asian pigs were introduced into Europe, where they crossed with wild boar. There appears to have been interbreeding with a now extinct ghost population of wild pigs during the Pleistocene. The genomes of domestic pigs show strong selection for genes affecting behavior and morphology. Human selection for domestic traits likely counteracted the homogenizing effect of gene flow from wild boars and created domestication islands in the genome.[27][28] Pigs arrived in Europe from the Near East at least 8,500 years ago. Over the next 3,000 years they interbred with European wild boar until their genome showed less than 5% Near Eastern ancestry, yet retained their domesticated features.[29]

DNA evidence from subfossil remains of teeth and jawbones of Neolithic pigs shows that the first domestic pigs in Europe were brought from the Near East. This stimulated the domestication of local European wild boar, resulting in a third domestication event with the Near Eastern genes dying out in European pig stock. More recently there have been complex exchanges, with European domesticated lines being exported, in turn, to the ancient Near East.[30][31] Historical records indicate that Asian pigs were again introduced into Europe during the 18th and early 19th centuries.[25]

History

[edit]

Columbian Exchange

[edit]

Among the animals that the Spanish introduced to the Chiloé Archipelago in the 16th century Columbian Exchange, pigs were the most successful in adapting to local conditions. The pigs benefited from abundant shellfish and algae exposed by the large tides of the archipelago.[32] Pigs were brought to southeastern North America from Europe by de Soto and other early Spanish explorers. Escaped pigs became feral.[33]

Feral pigs

[edit]
Main article: Feral pig
A family of feral pigs

Pigs have escaped from farms and gone feral in many parts of the world. Feral pigs in the southeastern United States have migrated north to the Midwest, where many state agencies have programs to remove them.[34][35][36] Feral pigs in New Zealand and northern Queensland have caused substantial environmental damage.[37][38] Feral hybrids of the European wild boar with the domestic pig are disruptive to both environment and agriculture, as they destroy crops, spread animal diseases including foot-and-mouth disease, and consume wildlife such as juvenile seabirds and young tortoises.[39] Feral pig damage is especially an issue in southeastern South America.[40][41]

Reproduction

[edit]

Physiology

[edit]
Reproductive system of the boar
Reproductive system of the sow

Female pigs reach sexual maturity at 3–12 months of age and come into estrus every 18–24 days if they are not successfully bred. The variation in ovulation rate can be attributed to intrinsic factors such as age and genotype, as well as extrinsic factors like nutrition, environment, and the supplementation of exogenous hormones. The gestation period averages 112–120 days.[42]

Piglets keeping warm together

Estrus lasts two to three days, and the female's displayed receptiveness to mate is known as standing heat. Standing heat is a reflexive response that is stimulated when the female is in contact with the saliva of a sexually mature boar. Androstenol is one of the pheromones produced in the submaxillary salivary glands of boars that trigger the female's response.[43] The female cervix contains a series of five interdigitating pads, or folds, that hold the boar's corkscrew-shaped penis during copulation.[44] Females have bicornuate uteruses and two conceptuses must be present in both uterine horns to enable pregnancy to proceed.[45] The mother's body recognises that it is pregnant on days 11 to 12 of pregnancy, and is marked by the corpus luteum's producing the sex hormone progesterone.[46] To sustain the pregnancy, the embryo signals to the corpus luteum with the hormones estradiol and prostaglandin E2.[47] This signaling acts on both the endometrium and luteal tissue to prevent the regression of the corpus luteum by activation of genes that are responsible for corpus luteum maintenance.[48] During mid to late pregnancy, the corpus luteum relies primarily on luteinizing hormone for maintenance until birth.[47]

Archeological evidence indicates that medieval European pigs farrowed, or bore a litter of piglets, once per year.[49] By the nineteenth century, European piglets routinely double-farrowed, or bore two litters of piglets per year. It is unclear when this shift occurred.[50] Pigs have a maximum life span of about 27 years.[51]

Nest-building

[edit]

A characteristic of pigs which they share with carnivores is nest-building. Sows root in the ground to create depressions the size of their body, and then build nest mounds, using twigs and leaves, softer in the middle, in which to give birth. When the mound reaches the desired height, she places large branches, up to 2 metres in length, on the surface. She enters the mound and roots around to create a depression within the gathered material. She then gives birth in a lying position, unlike other artiodactyls which usually stand while birthing.[52]

Nest-building occurs during the last 24 hours before the onset of farrowing, and becomes most intense 12 to 6 hours before farrowing.[53] The sow separates from the group and seeks a suitable nest site with well-drained soil and shelter from rain and wind. This provides the offspring with shelter, comfort, and thermoregulation. The nest provides protection against weather and predators, while keeping the piglets close to the sow and away from the rest of the herd. This ensures they do not get trampled on, and prevents other piglets from stealing milk from the sow.[54] The onset of nest-building is triggered by a rise in prolactin level, caused by a decrease in progesterone and an increase in prostaglandin; the gathering of nest material seems to be regulated more by external stimuli such as temperature.[53]

Nursing and suckling

[edit]

Pigs have complex nursing and suckling behaviour.[55] Nursing occurs every 50–60 minutes, and the sow requires stimulation from piglets before milk let-down. Sensory inputs (vocalisation, odours from mammary and birth fluids, and hair patterns of the sow) are particularly important immediately post-birth to facilitate teat location by the piglets.[56] Initially, the piglets compete for position at the udder; then the piglets massage around their respective teats with their snouts, during which time the sow grunts at slow, regular intervals. Each series of grunts varies in frequency, tone and magnitude, indicating the stages of nursing to the piglets.[57]

The phase of competition for teats and of nosing the udder lasts for about a minute, ending when milk begins to flow. The piglets then hold the teats in their mouths and suck with slow mouth movements (one per second), and the rate of the sow's grunting increases for approximately 20 seconds. The grunt peak in the third phase of suckling does not coincide with milk ejection, but rather the release of oxytocin from the pituitary into the bloodstream.[58] Phase four coincides with the period of main milk flow (10–20 seconds) when the piglets suddenly withdraw slightly from the udder and start sucking with rapid mouth movements of about three per second. The sow grunts rapidly, lower in tone and often in quick runs of three or four, during this phase. Finally, the flow stops and so does the grunting of the sow. The piglets may dart from teat to teat and recommence suckling with slow movements, or nosing the udder. Piglets massage and suckle the sow's teats after milk flow ceases as a way of letting the sow know their nutritional status. This helps her to regulate the amount of milk released from that teat in future sucklings. The more intense the post-feed massaging of a teat, the more milk that teat later releases.[59]

  • Sows typically have 12–14 nipples.
    Sows typically have 12–14 nipples.
  • A sow with suckling piglets
    A sow with suckling piglets

Teat order

[edit]

In pigs, dominance hierarchies are formed at an early age. Piglets are precocious, and attempt to suckle soon after being born. The piglets are born with sharp teeth and fight for the anterior teats, as these produce more milk. Once established, this teat order remains stable; each piglet tends to feed on a particular teat or group of teats.[52] Stimulation of the anterior teats appears to be important in causing milk letdown,[60] so it might be advantageous to the entire litter to have these teats occupied by healthy piglets. Piglets locate teats by sight and then by olfaction.[61]

Behaviour

[edit]

Social

[edit]
American Yorkshire pigs in a wallow

Pig behaviour is intermediate between that of other artiodactyls and of carnivores.[52] Pigs seek out the company of other pigs and often huddle to maintain physical contact, but they do not naturally form large herds. They live in groups of about 8–10 adult sows, some young individuals, and some single males.[53] Pigs confined in a simplified, crowded, or uncomfortable environment may resort to tail-biting; farmers sometimes dock the tails of pigs to prevent the problem, or may enrich the environment with toys or other objects to reduce the risk.[62][63]

Temperature control

[edit]

Because of their relative lack of sweat glands, pigs often control their body temperature using behavioural thermoregulation. Wallowing, coating the body with mud, is a common behaviour.[9] They do not submerge completely under the mud, but vary the depth and duration of wallowing depending on environmental conditions.[9] Adult pigs start wallowing once the ambient temperature is around 17–21 °C (63–70 °F). They cover themselves in mud from head to tail.[9] They may use mud as a sunscreen, or to keep parasites away.[9] Most bristled pigs "blow their coat", meaning that they shed most of the longer, coarser stiff hair once a year, usually in spring or early summer, to prepare for the warmer months ahead.[64]

Eating, feeding, sleeping

[edit]
Pigs around a rotary feeder

Where pigs are allowed to roam freely, they walk roughly 4 km daily, scavenging within a home range of around a hectare. Farmers in Africa often choose such a low-input, free-range production system.[65]

If conditions permit, pigs feed continuously for many hours and then sleep for many hours, in contrast to ruminants, which tend to feed for a short time and then sleep for a short time. Pigs are omnivorous and versatile in their feeding behaviour. They primarily eat leaves, stems, roots, fruits, and flowers.[66]

Rooting is an instinctual comforting behaviour in pigs characterized by nudging the snout into something. It first happens when piglets are born to obtain their mother's milk, and can become a habitual, obsessive behaviour, most prominent in animals weaned too early. Pigs root and dig into the ground to forage for food. Rooting is also a means of communication.[67]

Intelligence

[edit]
A pig using a specifically designed joystick[68]

Pigs are relatively intelligent animals, roughly on par with dogs. They distinguish each other as individuals, spend time in play, and form structured communities. They have good long-term memory and they experience emotions, changing their behaviour in response to the emotional states of other pigs. In terms of experimental tasks, pigs can perform tasks that require them to identify the locations of objects; they can solve mazes; and they can work with a simple language of symbols. They display self-recognition in a mirror. Pigs have been trained to associate different sorts of music (Bach and a military march) with food and social isolation respectively, and could communicate the resulting positive or negative emotion to untrained pigs.[69][70] Pigs can be trained to use a joystick with their snout to select a target on screen.[68]

Senses

[edit]
A trained pig using its sensitive nose to assist the search for wild truffles in France

Pigs have panoramic vision of approximately 310° and binocular vision of 35° to 50°. It is thought they have no eye accommodation.[71] Other animals that have no accommodation, e.g. sheep, lift their heads to see distant objects.[72] The extent to which pigs have colour vision is still a source of some debate; however, the presence of cone cells in the retina with two distinct wavelength sensitivities (blue and green) suggests that at least some colour vision is present.[73]

Pigs have a well-developed sense of smell; this is exploited in Europe where trained pigs find underground truffles.[74] Pigs have 1,113 genes for smell receptors, compared to 1,094 in dogs; this may indicate an acute sense of smell, but against this, insects have only around 50 to 100 such genes but make extensive use of olfaction.[75] Olfactory rather than visual stimuli are used in the identification of other pigs.[76] Hearing is well developed; sounds are localised by moving the head. Pigs use auditory stimuli extensively for communication in all social activities.[77] Alarm or aversive stimuli are transmitted to other pigs not only by auditory cues but also by pheromones.[78] Similarly, recognition between the sow and her piglets is by olfactory and vocal cues.[79]

Pests and diseases

[edit]
Trichinella spiralis larvae in uncooked pig meat

Pigs are subject to many pests and diseases which can seriously affect productivity and cause death. These include parasites such as Ascaris roundworms, virus diseases such as the tick-borne African Swine Fever, bacterial infections such as Clostridium, arthritis caused by Mycoplasma, and stillbirths caused by Parvovirus.[80]

Some parasites of pigs are a public health risk as they can be transmitted to humans in undercooked pork. These are the pork tapeworm Taenia solium; a protozoan, Toxoplasma gondii; and a nematode, Trichinella spiralis. Transmission can be prevented by thorough sanitation on the farm; by meat inspection and careful commercial processing; and by thorough cooking, or alternatively by sufficient freezing and curing.[81]

In agriculture

[edit]
Further information: Pig farming § Terminology

Production

[edit]
Main article: Pig farming

Pigs have been raised outdoors, and sometimes allowed to forage in woods or pastures. In industrialized nations, pig production has largely switched to large-scale intensive pig farming. This has lowered production costs but has caused concern about possible cruelty. As consumers have become concerned with the humane treatment of livestock, demand for pasture-raised pork in these nations has increased.[82] Most pigs in the US receive ractopamine, a beta-agonist drug, which promotes muscle instead of fat and quicker weight gain, requiring less feed to reach finishing weight, and producing less manure. China has requested that pork exports be ractopamine-free.[83] With a population of around 1 billion individuals, the domesticated pig is one of the most numerous large mammals on the planet.[84][85]

Like all animals, pigs are susceptible to adverse impacts from climate change, such as heat stress from increased annual temperatures and more intense heatwaves. Heat stress has increased rapidly between 1981 and 2017 on pig farms in Europe. Installing a ground-coupled heat exchanger is an effective intervention.[86]

  • Indoor pig farm, Sweden, 1911
    Indoor pig farm, Sweden, 1911
  • Sow in stall with separate piglet balcony to prevent crushing, Germany, 1959
    Sow in stall with separate piglet balcony to prevent crushing, Germany, 1959
  • Free range pigs with field shelters, England, 2006
    Free range pigs with field shelters, England, 2006
  • FAO data for 2021
  • Pork is tied with chicken as the most commonly consumed meat worldwide.
    Pork is tied with chicken as the most commonly consumed meat worldwide.
  • Pork production has grown substantially over the recent 60 years.
    Pork production has grown substantially over the recent 60 years.
  • Production of pork worldwide, by country in 2021.
    Production of pork worldwide, by country in 2021.

Breeds

[edit]
Main article: List of pig breeds

Around 600 breeds of pig have been created by farmers around the world, mainly in Europe and Asia, differing in coloration, shape, and size.[87] According to The Livestock Conservancy, as of 2016, three breeds of pig are critically rare (having a global population of fewer than 2000). They are the Choctaw hog, the Mulefoot, and the Ossabaw Island hog.[88] The smallest known pig breed in the world is the Göttingen minipig, typically weighing about 26 kilograms (57 lb) as a healthy, full-grown adult.[89]

As pets

[edit]
A mini pet pig

Given pigs are bred primarily as livestock and have not been bred as companion animals for very long, selective breeding for a placid or biddable temperament is not well established. Pigs have radically different psychology and behaviours compared to dogs, and exhibit fight-or-flight instincts, an independent nature, and natural assertiveness.[90] Male and female swine that have not been de-sexed may express unwanted aggressive behavior, and are prone to serious health issues.[91]

Economy

[edit]
Global pig stock
in 2019
Number in millions
1. China (Mainland)310.4 (36.5%)
2. European Union143.1 (16.83%)
3. United States78.7 (9.26%)
4. Brazil40.6 (4.77%)
5. Russia23.7 (2.79%)
6. Myanmar21.6 (2.54%)
7. Vietnam19.6 (2.31%)
8. Mexico18.4 (2.16%)
9. Canada14.1 (1.66%)
10. Philippines12.7 (1.49%)
World total850.3
Source: UN Food and Agriculture Organization

Approximately 1.5 billion pigs are slaughtered each year for meat.[92]

The pork belly futures contract became an icon of commodities trading. It appears in depictions of the arena in popular entertainment, such as the 1983 film Trading Places.[93] Trade in pork bellies declined, and they were delisted from the Chicago Mercantile Exchange in 2011.[93][94]

In 2023, China produced more pork than any other country, 55 million tonnes, followed by the European Union with 22.8 million tonnes and the United States with 12.5 million tonnes. Global production in 2023 was 120 million tonnes.[95] India, despite its large population, consumed under 0.3 million tonnes of pork in 2023.[96] International trade in pork (meat not consumed in the producing country) reached 13 million tonnes in 2020.[97]

Uses

[edit]

Products

[edit]

Pigs are farmed primarily for meat, called pork. Pork is eaten in the form of pork chops, loin or rib roasts, shoulder joints, steaks, and loin (also called fillet). The many meat products made from pork include ham, bacon (mainly from the back and belly), and sausages.[98] Pork is further made into charcuterie products such as terrines, galantines, pâtés and confits.[99] Some sausages such as salami are fermented and air-dried, to be eaten raw. There are many types, the original Italian varieties including Genovese, Milanese, and Cacciatorino, with spicier kinds from the South of Italy including Calabrese, Napoletano, and Peperone.[100]

The hide is made into pigskin leather, which is soft and durable; it can be brushed to form suede leather. These are used for products such as gloves, wallets, suede shoes, and leather jackets.[101] In the 16th century, pig skin was the most popular book-binding material in Germany, though calf skin was more common elsewhere.[102]

  • Pork chops
    Pork chops
  • Streaky or side bacon
    Streaky or side bacon
  • Salami, a fermented and air-dried sausage, originally made in Italy
    Salami, a fermented and air-dried sausage, originally made in Italy
  • A 16th century book bound in pig skin
    A 16th century book bound in pig skin
  • A woman's suede gloves, England, c. 1820
    A woman's suede gloves, England, c. 1820

In medicine

[edit]
The growth in publication of medical research papers using pigs and miniature pigs, and the research done on miniature pigs by organ system[103]

Pigs, both as live animals and as a source of post-mortem tissues, are valuable animal models because of their biological, physiological, and anatomical similarities to human beings. For instance, human skin is very similar to the pigskin, therefore pigskin has been used in many preclinical studies.[104][105]

Pigs are good non-human candidates for organ donation to humans, and in 2021 became the first animal to successfully donate an organ to a human body.[106][107] The procedure used a donor pig genetically engineered not to have a specific carbohydrate that the human body considers a threat–Galactose-alpha-1,3-galactose.[108] Pigs are good for human donation as the risk of cross-species disease transmission is reduced by the considerable phylogenetic distance from humans.[109] They are readily available, and the danger of creating new human diseases is low as domesticated pigs have been in close contact with humans for thousands of years.[110]

Impact of pig husbandry

[edit]

On public health

[edit]
Further information: Zoonotic disease

Pig farms can serve as reservoirs of viral diseases that are dangerous to humans and so contribute to their outbreaks in human populations.[111] The 2009 swine flu pandemic was caused by an influenza A variant which had first emerged in pigs.[112] Pigs were also essential to the first outbreak of the Nipah virus in 1999, with 93% of the infected humans having had contact with pigs.[111] While Japanese encephalitis is primarily spread by mosquitoes, pigs are a known intermediary host.[113] There is also a potential for porcine coronaviruses such as porcine epidemic diarrhea virus or swine acute diarrhea syndrome coronavirus to spill over into human populations.[111]

On the environment

[edit]
Main article: Environmental impact of pig farming
A typical waste lagoon in North Carolina

As with the other forms of meat, producing pork is more energy-intensive than plant-based foods, and it is associated with more greenhouse gas emissions per calorie. However, emissions from pork are many times smaller than those of beef, veal and mutton, though larger than of chicken meat.[114]

Intensive pig production is also associated with water pollution concerns, as the swine waste is often stored above ground in so-called lagoons. These lagoons typically have high levels of nitrogen and phosphorus, and can contain toxic heavy metals like zinc and copper, microbial pathogens, or hold elevated concentrations of pharmaceuticals from subtherapeutic antibiotic use in swine.[115] This wastewater from lagoons is liable to reach groundwater on farms, though there is little evidence for it reaching deeper into local drinking water supplies.[116] However, lagoon spills, such as from heavy rains in the wake of a hurricane, can lead to fish kills and algal blooms in local rivers.[115] In the United States, 35,000 mi (56,000 km) of river across over 20 states were estimated to have been contaminated by manure leakage as of 2015.[117] There is also evidence that evaporation from lagoons can cause nitrogen and phosphorus to spread through the air as dry particles then reach other water basins when they fall out through dry deposition. This process then also contributes to water eutrophication.[115]

On animal welfare

[edit]
Further information: Cruelty to animals § Welfare concerns of farm animals, and Intensive pig farming
Sows in gestation crates, United States, 2010

Intensive pig production involves practices such as castration, earmarking, tattooing for litter identification, tail docking, which are often done without the use of anesthetic.[118][119] Painful teeth clipping of piglets is also done to curtail cannibalism, behavioural instability and aggression, and tail biting, which are induced by the cramped environment.[120][121] In English indoor farming, young pigs (less than 110kg in weight) are allowed to be kept with less than one square meter of space per pig.[122]

Pigs often begin life in a farrowing or gestation crate, which is a small pen with a central cage, designed to allow the piglets to feed from their mother while preventing her from attacking or crushing them.[123] The crates are so small that the mother sows cannot turn around.[124][125] While wild piglets remain with their mothers for around 12 to 14 weeks, farmed piglets are weaned and removed from their mothers at between two and five weeks old.[126][127] Of the piglets born alive, 10% to 18% will not reach weaning age, instead succumbing to disease, starvation, dehydration, or accidental crushing by their mothers.[120][128] Unusually small runt piglets are typically killed immediately by staff through blunt trauma to the head.[129][130] Further, intensive farming involves sows giving birth to large litter sizes at an unnatural frequency, which increases the rate of stillborn piglets, and causes as many as 25%-50% of sows to die of prolapse.[131][132]

In culture

[edit]
Main article: Pigs in culture

Pigs, widespread in societies around the world since Neolithic times, have been used for many purposes in art, literature, and other expressions of human culture. In classical times, the Romans considered pork the finest of meats, enjoying sausages, and depicting them in their art.[133] Across Europe, pigs have been celebrated in carnivals since the Middle Ages,[134] becoming specially important in Medieval Germany in cities such as Nuremberg,[135] and in Early Modern Italy in cities such as Bologna.[136][137] Pigs, especially miniature breeds, are occasionally kept as pets.[138][139]

In literature, both for children[140] and adults, pig characters appear in allegories, comic stories, and serious novels.[134][141][142] In art, pigs have been represented in a wide range of media and styles from the earliest times in many cultures.[143] Pig names are used in idioms and animal epithets, often derogatory, since pigs have long been linked with dirtiness and greed,[144][145] while places such as Swindon are named for their association with swine.[146] The eating of pork is forbidden in Islam and Judaism,[147] but pigs are sacred in some other religions.[148][149]

References

[edit]

Further reading

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Pig

View on Grokipedia
from Grokipedia
The domestic pig (Sus scrofa domesticus) is a large, domesticated even-toed and subspecies of the Eurasian (Sus scrofa), classified within the family and order Artiodactyla. Originating from multiple independent events in regions including around 8,000–9,000 years ago and Southwest Asia during the period, pigs spread globally through and , with later European lineages arising from hybridization between imported Near Eastern pigs and local wild boars. As omnivorous mammals with anatomical and physiological similarities to s—including comparable gastrointestinal tracts and nutritional needs—pigs are valued in for production, where constitutes about 34% of global meat consumption, and in biomedical research for modeling human diseases and . They exhibit rooting behaviors for , live in social groups, and produce litters of 8–12 piglets after gestations of roughly 114 days, though intensive farming practices have raised empirical concerns over welfare, including tail docking and confinement, substantiated by higher stress indicators like elevated levels compared to less intensive systems.

Taxonomy and Evolutionary History

Phylogeny and Evolution

The family occupies a basal position within the order Artiodactyla (even-toed ungulates), specifically in the suborder , where it comprises a monophyletic sister to the Tayassuidae (peccaries). Molecular and evidence indicates that the divergence between Suidae and Tayassuidae occurred approximately 50 million years ago during the Eocene, following the initial radiation of artiodactyls in the early . This split predates the pseudogenization of the thermogenic gene in their common , a genetic reflecting reduced reliance on non-shivering suited to warmer climates. The fossil record of originates in during the Oligocene-Miocene transition, with definitive early members appearing by around 20 million years ago in the early . Subsequent diversification saw the emergence of the subfamily approximately 14–12 million years ago in the middle , which rapidly expanded across the , supplanting earlier suid lineages through competitive advantages in efficiency. Eurasian suids dispersed to via multiple colonizations, at least six documented events, facilitating adaptation to new ecosystems without ruminant competitors dominating browse. Ancestral forms resembling modern wild boars (Sus spp.) are evidenced in deposits, marking the establishment of lineages that persisted into the . Key evolutionary adaptations underpinning suid persistence include omnivory, enabled by brachyodont and versatile mechanics for processing , , and occasional vertebrates, which buffered against dietary shifts during climate fluctuations. The specialized, muscular —lacking a rostral but reinforced for leverage—facilitated rooting behavior, allowing efficient soil disturbance to access buried tubers and , a trait conserved from ancestors. High , with litters supporting rapid population rebound, combined with these innovations, conferred resilience across -to-Holocene transitions, including glacial-interglacial cycles and .

Taxonomy

The domestic pig is taxonomically classified within the genus Sus of the family Suidae, order Artiodactyla. The binomial nomenclature designates the Eurasian wild boar as Sus scrofa Linnaeus, 1758, with the domestic form recognized as the subspecies Sus scrofa domesticus Erxleben, 1777, reflecting its derivation from wild progenitors through selective breeding and human management. However, the American Society of Mammalogists treats the domestic pig as a distinct species, Sus domesticus, distinguishing it from the wild S. scrofa based on morphological and genetic divergences accumulated under domestication. The genus Sus encompasses approximately 10–12 species, primarily distributed across and , including the Sulawesi warty pig (Sus celebensis), bearded pig (Sus barbatus), and (Sus cebifrons), differentiated from S. scrofa by traits such as wattles, body proportions, and preferences. Subspecies within S. scrofa number over 16, varying geographically across , , and North Africa; examples include the (S. s. leucomystax) with coarser bristles and the (S. s. cristatus) with straighter tusks, delineated by regional adaptations in morphology, pelage texture, and size. Taxonomic delineation in Sus relies on integrated criteria: morphology (e.g., , , and limb robustness), genetics (e.g., mitochondrial sequences and nuclear loci revealing phylogeographic clusters), and geography (e.g., allopatric distributions limiting ). Hybridization complicates boundaries, as domestic S. scrofa domesticus interbreeds with wild S. scrofa and, less commonly, other Sus species like S. celebensis in regions such as , producing fertile offspring with intermediate traits documented via craniometric and genomic analyses. Debates persist over feral populations, which descend from escaped domestic pigs and often hybridize with , resulting in genotypes where up to 97% of invasive North American wild pigs exhibit admixed ancestry; taxonomists argue whether these warrant reclassification as S. scrofa hybrids or distinct feral forms, emphasizing genetic assays over phenotypic reversion to wild-like morphology.

Domestication

Pigs were domesticated from (Sus scrofa) independently in at least two primary centers during the period, approximately 10,000–9,000 years ago. In the , particularly eastern , archaeological evidence from sites such as and Hallan Çemi reveals early management of boar populations around 10,500–10,000 years ago, characterized by age-biased mortality profiles favoring younger animals and initial size reductions indicative of under human control. Concurrently in , remains from the Cishan site in Province, dated to about 8,000 (circa 6000 BCE), show domesticated pigs with smaller metacarpals, isolated from local through reproductive management, marking one of the earliest instances of pig husbandry in . These events reflect human adaptation to sedentary lifestyles, where pigs provided a reliable protein source via scavenging and herding, distinct from hunting wild progenitors. Mitochondrial DNA and whole-genome analyses of ancient remains substantiate multiple origins, with Western Eurasian pigs tracing to Near Eastern via haplogroups Y1 and Y2, while East Asian lineages derive from indigenous S. scrofa populations through haplogroups A, C, and D, showing minimal early admixture between regions. Genomic scans reveal selective sweeps in domestic pigs at loci linked to neural development and , correlating with diminished and responses compared to 's territoriality and high flight distances, enabling tolerance of proximity and enclosure life. Alterations in genes regulating , such as those influencing binding and deposition, emerged under early pressures favoring efficient feed conversion and higher fat yields, traits absent or minimal in leaner adapted to . Initial human selection prioritized docility and manageability over wild boar's solitary or small-group dynamics, with evidence from kill-off patterns suggesting culling of aggressive adults to propagate calmer individuals suitable for containment. Reproductive traits underwent rapid change, as domestic litters exceeded wild boar's typical 4–6 piglets per farrowing, with early Chinese assemblages indicating averages approaching 8–10 through selective retention of prolific sows, enhancing for sustenance. These pressures, driven by caloric needs in emerging agrarian societies, contrasted sharply with wild boar's seasonal breeding and dispersal, yielding lineages reproductively isolated by 8,000 years ago in both regions.

Physical Characteristics

Anatomy and Physiology

The skeletal of the pig consists of a robust framework adapted for , featuring even-toed characteristics with four hoofed toes per foot, wherein the two central toes bear the majority of body weight. The includes a specialized elongated reinforced by a prenasal and a cartilaginous disk at the tip, providing structural support for sensory and manipulative functions. Pigs lack functional sweat glands, rendering ineffective for ; instead, they depend on cutaneous facilitated by in or water, which cools the body as moisture evaporates from the skin. This physiological limitation, combined with high body insulation from subcutaneous , necessitates such behavioral adaptations to prevent in warm environments. The digestive system is , comprising a simple stomach for initial breakdown via and , followed by enzymatic in the . However, pigs exhibit hindgut fermentation capacity in the and colon, where symbiotic microbes degrade non-starch and other fibers, yielding volatile fatty acids for energy absorption and supporting omnivorous adaptations by enhancing utilization of plant-based feeds alongside animal matter. Circulatory and respiratory physiologies in pigs facilitate efficient and transport, with a four-chambered heart and lobed lungs enabling high oxygen uptake relative to body mass. These systems underpin rapid post-weaning growth, with juveniles capable of average daily gains approaching 1 kg under commercial rearing conditions optimized for feed efficiency and health.

Size, Appearance, and Variations

Wild boars (Sus scrofa), the progenitor of domestic pigs, exhibit body lengths of 152–183 cm, shoulder heights of 76–91 cm, and weights ranging from 68–100 kg in typical adults, though exceptional males in some populations exceed 180 kg. Males display pronounced sexual dimorphism, being 20–30% heavier than females and possessing larger, continuously growing tusks that can reach 25 cm in length, used for defense and foraging, while females have smaller, vestigial tusks. Their coat consists of coarse, bristly hair forming a thick undercoat and mane along the spine for insulation and camouflage in forested habitats, with overall dark brown to black pigmentation aiding concealment amid undergrowth. Domestic pigs show extensive morphological variation due to selective breeding over millennia, with mature boars in commercial breeds like the Tamworth reaching 250–372 kg and sows 200–300 kg, far exceeding wild ancestors, while miniature breeds such as the Guinea hog top out at 68–136 kg and 38–51 cm shoulder height. Coat diversity includes sparse, fine hairs in many breeds—often nearly hairless—contrasting the wild type's dense bristles, with feral escapees reverting to thicker coats and tusk growth within months. Colors range from solid white (e.g., Yorkshire), black (Berkshire), red (Duroc), to spotted or belted patterns, resulting from mutations in genes like MC1R selected for aesthetic or economic traits rather than natural camouflage. Skin pigmentation in domestic forms often appears pink or light due to reduced and sparse exposing underlying tissue, unlike the darker, protective hides of wild boars that provide UV resistance and blending with soil; this correlates with but increases sunburn risk in exposed breeds. persists in domestics, with males generally 10–20% larger in mass than sows across breeds, though breeding has amplified size disparities in meat-focused lines.

Reproduction

Physiology and Breeding

The in domestic sows typically lasts 21 days, with estrus (standing heat) enduring 36–48 hours in gilts and 48–72 hours in multiparous sows. Pigs exhibit induced , where the physical stimulus of or hormonal analogs triggers (LH) release, leading to 24–48 hours post-stimulation; without such induction, spontaneous is rare. Follicular development occurs in the 5–6 days preceding estrus, driven by (FSH) and peaks, after which corpora lutea form and secrete progesterone to maintain potential . Gestation in sows averages 114–115 days (precisely 3 months, 3 weeks, and 3 days in many breeds), during which embryos implant by day 30, with fetal losses peaking early if nutritional or stress factors intervene. Litters commonly comprise 10–12 piglets in modern breeds, reflecting selective pressures for high , though uterine capacity limits effective carrying to around 12–14 fetuses. This elevated reproductive output imposes physiological strain, as sows partition substantial energy toward placental and fetal growth—up to 40–50% of maternal in late —often necessitating body reserve mobilization if feed intake fails to match demands, risking sow condition and subsequent fertility. In boars, initiates around 4–6 months of age, with marked by first spermatozoa at 17–18 weeks and full by 6–7 months; peak aligns with 18 months, when and optimize. Each spermatogenic cycle spans approximately 8.6–9 days, yielding high sperm output from seminiferous tubules occupying 87% of testicular . leverages this by extending one boar's reach to roughly 2,000 sows annually via liquid-preserved , achieving farrowing rates comparable to mating (85–90%) when doses contain 2–3 billion viable spermatozoa, though efficacy hinges on timing within estrus and handling to minimize damage. High-fecundity breeding amplifies maternal energy costs, as sows in prolific lines exhibit elevated and tissue during , potentially curtailing yield or inter-litter intervals without compensatory .

Maternal Behavior

Domestic sows exhibit a strong instinct for nest-building prior to farrowing, typically intensifying 24 hours before parturition, involving rooting, pawing, and gathering materials such as straw, grass, or twigs to create a protective structure. This behavior, observed even in confined indoor environments without suitable materials, serves primarily for thermoregulation of vulnerable newborn piglets, which lack effective shivering and fur insulation, maintaining nest temperatures around 30–35°C to prevent hypothermia. Post-farrowing, the sow remains recumbent in the nest, facilitating initial suckling bouts that occur frequently, averaging 25–31 times per 24 hours in the first week, with piglets massaging the udder for 2–5 minutes to stimulate milk let-down followed by a 10–15 second ejection phase. Within hours of birth, suckling piglets establish a teat order through competition and fighting, peaking around 3 hours postpartum, resulting in a stable by the end of the first week where larger, heavier piglets typically claim anterior producing higher volumes, while smaller ones occupy posterior positions with lesser yield. This order influences growth disparities, as anterior-teat piglets gain more weight due to increased intake, with minimal switching thereafter except in cases of teat failure. The sow reinforces this by selective responses, ensuring even distribution while the piglets' vocal and physical cues maintain bout synchronization. Natural weaning in observed semi-natural settings occurs gradually between 12 and 17 weeks of age, marked by decreasing suckling frequency and the sow's increasing aggression toward older offspring, including grunting, pushing, or attacking to deter nursing attempts and encourage independence. This maternal rejection aligns with the piglets' maturation, shifting diet from to feed, though commercial practices often impose earlier separation at 3–4 weeks, disrupting these ethological patterns and elevating stress indicators. Sows may vocalize distress initially but adapt, prioritizing rebreeding readiness over prolonged .

Behavior and Cognition

Social Behavior

Wild pigs in their natural habitats form stable social groups known as sounders, typically comprising 6 to 20 individuals centered around related adult females and their , with provided by a dominant matriarch sow. These matrilineal units exhibit a linear , where older and larger sows assert priority access to resources through aggressive displays such as charging, , or pushing, while subordinates signal submission via postures like averting gaze or fleeing. Adult males remain largely solitary outside breeding seasons, dispersing from natal groups to minimize risks, thereby promoting within sounders through outbreeding with unrelated females. ![Wild hogs in a family group][float-right]
Social coordination within sounders relies heavily on vocal communication, with grunts serving as primary signals for maintaining group cohesion during movement or positive interactions, such as greeting kin or expressing contentment. Higher-pitched screams or squeals indicate distress, alerting group members to threats like predators and prompting evasive maneuvers, as observed in field studies of populations. These vocal patterns facilitate rapid information sharing in dynamic environments, enhancing survival without requiring visual contact. Mutual social behaviors, including occasional allogrooming where individuals nuzzle or rub against one another, reinforce bonds and reduce tension in hierarchical groups, particularly among females and juveniles. In domestic settings derived from wild ancestors, similar dynamics persist, though confinement can intensify if hierarchies are disrupted, underscoring the adaptive value of these innate structures for group stability.

Foraging, Feeding, and Daily Activities

Pigs maintain an omnivorous diet in wild populations, dominated by plant matter comprising approximately 90% of intake by volume, including acorns, roots, tubers, grasses, and fruits, with the remainder consisting of animal matter such as , small vertebrates, eggs, and carrion. This composition reflects opportunistic feeding adapted to seasonal availability, with higher animal consumption in introduced ranges where fungi and supplement scarce . Foraging primarily occurs through rooting, where pigs use their muscular snouts equipped with a disc-like to dig and overturn , efficiently unearthing tubers, , fungi, and burrowing buried up to 30 cm deep. This , observed across wild and populations, disrupts while maximizing access to nutrient-dense underground resources unavailable via surface . Daily activity follows circadian rhythms, with pigs allocating substantial time to bouts that align with environmental cues like and availability, often peaking in crepuscular periods to avoid diurnal heat or predation. relies on behavioral strategies due to sparse functional sweat glands, which produce minimal insufficient for cooling; instead, pigs wallow in or water to facilitate evaporative heat loss and protect skin from parasites and sunburn. frequency increases with ambient temperatures above 20°C, serving as a primary mechanism to maintain core body temperature below 39°C. Rest phases total approximately 8 hours per day, predominantly nocturnal, comprising drowsiness, , and rapid eye movement (REM) episodes averaging 3.3 minutes each, with sleep cycles of about 13 minutes suggesting neural consolidation akin to other mammals. Roughly 80% of these cycles occur at night, balancing energy expenditure from extended .

Intelligence and Problem-Solving

Pigs demonstrate advanced spatial learning and memory capabilities, as evidenced by their performance in navigation tasks. In automated T- experiments, pigs exhibit reliable spatial , navigating to rewarded arms while avoiding previously visited ones, validating the task as a measure of cognitive function comparable to models. Studies also indicate pigs achieve understanding akin to that of a around three years old, recognizing that hidden objects continue to exist and using this knowledge to retrieve rewards. Recent assessments place pig cognitive abilities at or above those of dogs in such as and flexibility, with pigs outperforming dogs in several metrics as of 2024 evaluations. Pigs display problem-solving skills through tool manipulation and . In controlled trials, domestic pigs (Sus scrofa) learned to operate a with their snouts to control a cursor in a video task, aligning it with on-screen targets for rewards, despite anatomical limitations like poor dexterity and . This acquisition highlights behavioral flexibility, with pigs improving performance over sessions and generalizing the skill to novel setups. Individual pigs have solved physical puzzles, such as shape-sorting tasks, completing them in under a minute by manipulating blocks into slots, demonstrating rapid trial-and-error learning and persistence. Regarding self-referential , pigs show instrumental use of mirrors but limited evidence of full self-recognition. Experiments reveal pigs learn to interpret mirror images as representations of , using them to locate hidden food beyond direct line-of-sight, indicating awareness of visual mapping rather than mere avoidance or . They do not consistently pass modified mark tests requiring self-directed responses to body markings visible only in reflection, fueling ongoing debate about the depth of . Causal reasoning appears in puzzle contexts, where pigs infer object interactions to achieve goals, supported by neural underpinnings linked to genetic factors. Genomic analyses identify over 100 candidate genes in pigs associated with , , and neural development, influencing brain regions like the hippocampus and tying heritable traits to under .

Sensory Capabilities

Pigs possess an exceptionally developed , underpinned by a encoding approximately 1,113 functional genes, surpassing the roughly 396 functional genes in humans. This olfactory repertoire enables detection of odors at concentrations as low as parts per trillion; for instance, their sensitivity to certain odors like n-butanol is approximately 2,000 times greater than humans', detecting it at about 2 parts per trillion compared to human thresholds around 40 parts per billion. This capability is facilitated by the comprising about 7% of total brain volume—far exceeding the 0.01% in humans. The system includes large clusters of olfactory receptor subfamilies with low rates (around 14.5%), enhancing allelic diversity for broad scent discrimination. In vision, domestic pigs exhibit dichromatic color via two types: short-wavelength-sensitive cones peaking at 439 nm (blue-violet) and medium-wavelength-sensitive cones peaking in the green , without dedicated red-sensitive cones. Their ocular media permit high transmission of wavelengths, suggesting sensitivity to UV light beyond human capabilities, potentially aiding in environmental cue detection. Auditory capabilities span 42 Hz to 40.5 kHz, with peak sensitivity from 250 Hz to 16 kHz, allowing of ultrasonic frequencies inaudible to s and relevant for . The supports this extended high-frequency range, with behavioral thresholds confirming acuity up to these limits. The snout's apical disk harbors a dense of mechanoreceptors, conferring tactile acuity akin to human fingertips for texture discrimination and spatial mapping. Proprioceptive and vestibular systems provide integrated feedback for head and body positioning, with and proprioceptors in neck musculature enabling precise orientation during locomotion independent of visual input.

Health and Diseases

Common Diseases and Pathogens

Porcine reproductive and respiratory syndrome (PRRS), caused by the PRRS virus (PRRSV) in the Arteriviridae family, is a widespread affecting herds globally. It manifests as reproductive failures in sows, including abortions, stillbirths, and weak-born piglets, alongside respiratory distress, , and secondary infections in nursery and grower pigs. Transmission primarily occurs through direct contact with infected animals, contaminated , body fluids, or fomites, with limited airborne spread possible. In severe outbreaks, particularly with virulent strains, mortality can reach up to 20% in weaning and grower-finisher pigs due to exacerbated respiratory complications. Foot-and-mouth disease (FMD), induced by the (FMDV) of the Picornaviridae family, represents another highly contagious viral pathogen in pigs, though eradicated from regions like the . Clinical signs include high fever, excessive salivation, lameness, and vesicular lesions (blisters) on the , , feet, and teats, leading to reduced feed intake and production. Pigs serve as efficient amplifiers of the virus, excreting high titers in aerosols, saliva, and , facilitating rapid transmission via direct contact, airborne particles over distances up to several kilometers under favorable conditions, or contaminated objects and animal products; incubation averages 1-2 days in pigs. While direct mortality is low, outbreaks cause substantial production losses through culling and trade restrictions. Among bacterial infections, , caused by , commonly affects pigs over 12 weeks of age, presenting in acute septicemic form with sudden deaths, high fever (up to 42°C), reluctance to move, and characteristic rhomboid ("diamond") erythematous skin lesions, or in chronic form with , lameness, and valvular . Transmission happens via ingestion of contaminated feed, water, or soil harboring the bacterium from carrier pigs or environment, with outbreaks more frequent in unvaccinated or stressed herds during warm weather. The disease carries zoonotic risk through cutaneous exposure, though incidence in commercial settings has declined with . Swine brucellosis, attributable to suis, induces reproductive disorders such as abortions, , and in boars, with transmission through venereal routes, of contaminated tissues, or contact with aborted fetuses. In the United States, the disease was eliminated from commercial herds by 2011 through testing and slaughter, rendering it rare therein, but persists in swine populations with seroprevalence varying from 0.3% to over 50% across states, posing spillover risks to domestic pigs. It exhibits zoonotic potential, causing undulant fever and complications in humans via direct contact or consumption of unpasteurized products, though human cases linked to swine remain infrequent. Prion diseases, while not classically prevalent in pigs, present chronic wasting risks; experimental and field data indicate pigs can accumulate from cervid (CWD) via oral exposure or scavenging, with detection in lymphoid and muscle tissues of wild pigs in CWD-endemic U.S. areas, potentially establishing subclinical reservoirs without overt clinical signs in swine.

Parasites and Pests

Pigs are susceptible to various endoparasites, particularly nematodes such as , the large roundworm that resides in the . The lifecycle involves eggs passed in feces that embryonate in the environment and can remain viable for up to 10 years under suitable conditions; infective eggs are ingested by pigs, hatch in the gut, and larvae migrate through the liver and lungs before returning to the intestines to mature. This migration causes liver lesions known as "milk spots," while adult worms compete for nutrients, leading to reduced feed efficiency and growth rates in affected young pigs, with heavier burdens exacerbating on suboptimal diets. Ectoparasites like the mite var. suis cause sarcoptic , burrowing into the skin to induce intense pruritus, papules, and thickened lesions, often starting on the head and ears before spreading. Infestations are more prevalent in outdoor or extensive systems due to direct contact and environmental reservoirs, contrasting with lower rates in biosecure indoor facilities. Control relies on topical or injectable acaricides such as , which effectively eliminate mites when applied farm-wide to break transmission cycles. Rodents, including rats and mice, serve as pests in pig operations by consuming and contaminating feed, gnawing infrastructure, and vectoring pathogens like Salmonella spp. and leptospirosis through feces and urine. Infestation levels are empirically higher in older or poorly maintained facilities, with rodents capable of introducing millions of bacterial cells daily, though reduces densities by targeting harborage and food sources. Avian pests, such as wild birds, mechanically transmit porcine diseases like transmissible via droppings and direct contact, particularly in open-air systems where birds access feed or interact with pigs. Pigs exhibit varying immunity to parasites, with older animals developing partial resistance through prior exposure, though piglets remain highly vulnerable; nutritional enhancements, including trace minerals, bolster immune responses and reduce susceptibility. with anthelmintics like benzimidazoles achieves near-100% against common nematodes when timed to lifecycle stages, such as pre-farrowing in sows to minimize piglet transmission. Strategic programs, including fecal counts for targeted treatment, outperform routine dosing in sustaining amid potential resistance development.

Recent Disease Challenges

African Swine Fever (ASF) has persisted as a primary transboundary threat to swine health, with outbreaks in domestic pigs and wild boars reported across and in 2024 and 2025. In the , domestic pig outbreaks fell to 333 in 2024, reflecting an 83% decline from 2023 due to intensified surveillance and control measures, though the virus maintained footholds in 13 member states. Early 2025 data indicated ongoing activity, including surges in and relative to prior years. In , 151 new domestic pig outbreaks and 198 in wild boars were documented by 2025, alongside fresh incidents in India's districts in July and . A prominent European case occurred in in early 2025, where ASF infected a farm holding approximately 20,000 pigs, necessitating full depopulation and underscoring vulnerabilities in large-scale operations despite regional risk assessments. Control strategies emphasize —such as restricted farm access, waste management, and population management—over unattainable eradication, given the virus's environmental stability and in feral swine that enable reintroduction. No licensed exists for ASF, leading to reliance on and movement bans; combined outbreaks in and in 2025 prompted the destruction of nearly 50,000 pigs, amplifying economic losses through direct mortality, indemnity costs, and disrupted . Globally, ASF has inflicted billions in damages since 2018, with 2024–2025 incidents reinforcing the need for farmer compliance in smallholder and commercial settings to curb spillover. Emerging genetic interventions provide cautious optimism for disease resilience. In October 2025, CRISPR-edited pigs demonstrated complete immunity to (CSF)—a distinct from ASF but similarly devastating—by disrupting the receptor essential for viral entry, with edited animals showing no symptoms or post-challenge. For ASF, no equivalent edited resistance has been field-tested in swine by late 2025, though natural tolerance in African breeds links to variants like polymorphisms, informing ongoing preclinical research into targeted edits amid regulatory hurdles. These approaches complement, rather than replace, , as incomplete penetration in breeding populations could still permit outbreaks.

Human Interaction and History

Historical Domestication and Spread

Domestic pigs disseminated across following initial domestication through migrations and trade, including Indo-European expansions that carried them into northern and western regions, where genetic evidence indicates admixture with local populations. Along the , historical pig trading contributed to range expansions and gene flow between eastern domestic lineages and central Asian wild stocks, as suggested by patterns of sharing. In the Pacific, Austronesian voyagers transported pigs as a key domesticate during Lapita expansions into , with analyses confirming their introduction to Polynesian islands via long-distance canoe voyages; for instance, pigs reached circa AD 1200, supporting settlement and cultural practices. Medieval European pig rearing intensified under feudal systems, with pigs providing a primary protein source through in common woodlands, where herds foraged on acorns and mast; monastic often managed substantial pig populations, integrating breeding with agricultural routines to supply communities and pilgrims. The saw pig breed standardization accelerate in amid industrialization and rising urban demand for , with Britain leading through programs that produced uniform types like the Large White, whose societies formalized traits for meat yield and exported globally starting in the 1880s.

Columbian Exchange and Global Distribution

introduced domestic pigs (Sus scrofa domesticus) to the during his second voyage in 1493, transporting them from the to the island of in the . These pigs, derived from Eurasian lineages, rapidly established self-sustaining populations due to their high reproductive rates—sows can produce litters of 6–12 piglets multiple times per year—and opportunistic foraging habits, which allowed them to thrive on local vegetation, roots, and without reliance on human feed. This introduction marked the onset of the for swine, facilitating the transfer of livestock to the and enabling European explorers to maintain protein supplies during voyages and inland treks. Spanish expeditions further disseminated pigs across the in the , with landing in in 1539 accompanied by an initial herd of 13 pigs as part of his expedition's provisions. By the time of de Soto's death in 1542, the population had expanded to approximately 700 through natural increase and strategic releases to provision return routes or restock escaped animals. Pigs served a critical nutritional role in colonization, offering portable, high-calorie meat that could be salted or consumed fresh, sustaining crews and settlers in regions lacking other domesticated herbivores suited to tropical and subtropical climates. Their ability to independently reduced logistical burdens, contrasting with less adaptable like sheep, and supported the establishment of early outposts from the to the . No genetic admixture occurred between introduced pigs and native New World suids such as peccaries (Tayassuidae family), which belong to a distinct evolutionary lineage from true pigs (Suidae) and exhibit incompatible reproductive biology. Instead, rapid adaptation arose from the domestic pigs' pre-existing omnivorous flexibility and resilience, enabling feral descendants to exploit diverse habitats from forests to wetlands without interbreeding. This ecological opportunism propelled their spread southward into Mexico and Central America via subsequent Spanish conquests, and northward through French and English colonies. From the 16th to 18th centuries, pig distribution expanded globally through colonial networks, with receiving primary influxes that integrated into settler diets and local economies. In North American colonies, pig numbers reached thousands by 1660 in areas like , where smallholders typically maintained 4–5 animals per farm by the late 1600s, fostering self-sufficient production that influenced consumption patterns across European outposts. These developments laid foundational circuits, as cured barrels became staples for transatlantic shipping and inter-colonial exchange, embedding swine as a versatile in emerging global systems without reliance on pre-existing New World .

Feral and Wild Populations

Feral swine populations in the United States consist primarily of escaped or released domestic pigs that have reverted to a state, often hybridizing with introduced Eurasian wild boars (Sus scrofa), resulting in approximately 97% of individuals exhibiting hybrid . These hybrids display toward wild-type traits, such as longer snouts, coarser bristles, and prominent tusks, driven by favoring survival in uncultivated environments where domestic features like high fat content become disadvantageous. Over time, repeated escapes from farms and deliberate releases for have led to self-sustaining herds that expand rapidly due to high reproductive rates—sows can produce two litters annually with 6-12 piglets each—and adaptability to diverse habitats from forests to wetlands. In the , feral swine number between 6 and 9 million, occupying at least 35 states with the highest densities in , , and Georgia, where populations continue to grow despite control measures. Their rooting behavior devastates crops, with annual agricultural damages estimated at $2.5 billion, including direct consumption of grains, soybeans, and , as well as that reduces future yields. Ecologically, they contribute to the decline of nearly 300 by predating ground-nesting birds' eggs, competing with native ungulates for , and altering habitats through and that promotes invasive plant spread while degrading . These impacts are density-dependent, intensifying in areas with unchecked herd growth. Management focuses on eradication through integrated methods, including corral —which removes 0.20 to 0.43 pigs per person-hour—and targeted , supported by USDA programs that have eradicated populations in several states since 2014. While recreational generates revenue and engages landowners, it often disperses surviving pigs rather than reducing overall numbers, as intelligent survivors learn to evade hunters and reproduce prolifically; experts emphasize and exclusion for sustained population suppression over reliance on harvest. Some hunters advocate managing as a for meat and trophies, citing their abundance, but empirical data indicate this approach fails to offset ecological costs or achieve local eradication without aggressive . Genetic monitoring aids efforts by tracing illegal translocations that accelerate spread.

Pig Farming and Agriculture

Production Systems

Intensive pig production systems, often implemented as concentrated animal feeding operations (CAFOs), confine animals in climate-controlled barns to maximize growth efficiency and scale. These systems typically achieve a feed conversion ratio (FCR) of 2.6 to 3.0 kilograms of feed per kilogram of body weight gain in the grow-finish phase, reflecting optimized nutrition and environmental controls that minimize energy expenditure on thermoregulation or foraging. In contrast, extensive pasture-based systems, where pigs have access to outdoor areas for foraging, exhibit higher FCR values, often exceeding 3.5 kg/kg, due to increased physical activity, variable feed quality, and exposure to environmental stressors that slow weight gain. CAFOs employ systems, such as tunnel or cross-ventilation, to regulate , , and air quality, which supports faster growth rates by reducing heat stress and incidence compared to unventilated traditional setups. in these operations commonly involves flushing into anaerobic lagoons for storage and partial treatment, enabling high-density —up to 1 square meter per pig—while concentrating nutrients for later land application, though this raises environmental concerns from nutrient runoff. use in intensive systems, historically including subtherapeutic doses for growth promotion, has contributed to gains of 5-10% in average daily gain and feed efficiency by curbing infections in crowded conditions, though regulatory bans in regions like the since 2006 have prompted shifts to alternatives without major output declines. Overall, intensive systems double or more the output per land unit dedicated to housing relative to traditional extensive methods, as high stocking densities and batch production (all-in-all-out) allow for rapid turnover and reduced land requirements per kilogram of pork produced, prioritizing scale over per-animal space. This efficiency stems from controlled biosecurity and genetics tailored for confinement, though it demands precise management to mitigate disease amplification risks inherent to density.

Breeds and Selective Breeding

Domestic pig breeds have been developed through centuries of to optimize traits such as growth rate, meat quality, and reproductive performance. Major commercial breeds include maternal lines like the (also known as Large White), valued for high lean meat yield, muscularity, and low backfat, making it a cornerstone for and lean production. Terminal sire breeds such as the Duroc emphasize marbling, which enhances meat tenderness, juiciness, and flavor, distinguishing it from leaner counterparts. Other prominent breeds include the , selected for lean muscle and minimal backfat, and the , noted for prolificacy and longevity in breeding programs. Heritage breeds, such as the Gloucester Old Spot and , contrast with modern commercial hybrids by retaining traits adapted to extensive systems, including higher content for flavor and resilience in varied environments, though they grow more slowly than hybrids optimized for intensive confinement. Commercial production often employs crossbreeding between purebred lines, such as Yorkshire-Landrace maternal hybrids with Duroc sires, to exploit for improved growth, feed efficiency, and uniformity. Artificial selection has targeted reproductive traits, with average litter sizes increasing to 16 or more piglets through breeding for total number born and number born alive, though larger litters can reduce individual piglet viability if not balanced with birth weight uniformity. Efforts also focus on resilience, selecting for genetic factors that enhance coping with pathogens like PRRSV, reducing reliance on interventions amid rising concerns.
BreedPrimary TraitsUsage
Lean meat, muscular frame, low backfatMaternal line, production
DurocMarbling, tenderness, flavorTerminal , quality
Lean muscle, large eyeTerminal , carcass quality
High , sizeReproductive research, heritage
Inbreeding within pure lines risks depression in traits like litter size and growth, with reductions of up to several piglets per full inbreeding coefficient; crossbreeding mitigates this by restoring vigor and avoiding homozygous deleterious alleles.

Genetic Engineering and Modern Advances

In 2025, researchers at the University of Edinburgh's utilized CRISPR-Cas9 gene editing to knock out the DNAJC14 gene in pigs, rendering them completely resistant to (CSFV), a highly that causes significant economic losses in global swine production. The modification prevented viral replication without observable adverse effects on pig health or growth, demonstrating the precision of targeted edits to enhance resistance while preserving natural . Similarly, in May 2025, the U.S. (FDA) approved gene-editing technology developed by PIC to produce pigs resistant to porcine reproductive and respiratory syndrome (PRRS), a costing the industry billions annually through reduced and mortality. These edited pigs exhibited no upon exposure and were deemed safe for human consumption, marking a regulatory milestone for intentional genomic alterations in . Earlier transgenic approaches incorporated bovine (bGH) genes into pigs, resulting in up to 15-20% improvements in daily and feed across generations, though some lines showed variable reduction and potential welfare issues like leg abnormalities. Modern refinements combine such enhancements with for multi-trait editing, targeting genes for muscle growth and to optimize carcass yield without compromising . Vaccine advancements, including RNA-based platforms, complement genetic edits by providing herd-level immunity against pathogens like African swine fever, reducing reliance on antibiotics and . Integration of (AI) and has accelerated genetic selection by predicting breeding outcomes with 10-50% higher accuracy than traditional methods, using genomic data to forecast traits like disease resistance and growth rates. For instance, AI models analyze SNP markers to prioritize sires and dams, shortening generation intervals and amplifying gains in polygenic traits. Regulatory frameworks, such as FDA evaluations, emphasize safety data from controlled trials, confirming no off-target effects or allergenicity before market entry, though international approvals vary due to differing risk assessments. These advances prioritize empirical validation over precautionary restrictions, enabling scalable improvements in pig resilience and productivity.

Economic Importance

Global Production and Trade

Global pork production reached approximately 116.4 million metric tons (MMT) in 2023/2024, with forecasts indicating a marginal increase to 116.45 MMT in 2024/2025. dominates output, accounting for 49% of the total at 57.06 MMT in 2024, followed by the at 18% with 21.25 MMT. The contributes around 12.6 MMT annually, while Brazil's production expanded to 4.8 MMT in 2024, reflecting a 4.9% year-over-year growth driven by domestic demand and export expansion. These figures underscore Asia's lead in volume, with alone representing nearly half of worldwide supply amid ongoing recovery from prior disruptions. International trade in pork products emphasizes exports from efficient producers, with the projected as the largest exporter in 2024, followed closely by the . Key players include and within the EU, , and an ascending , which exported to over 100 countries in 2024 and anticipates a 5% volume increase in 2025. Global pork exports are forecasted to rise 2% to 10.4 MMT in 2024, with significant flows in processed items like and ; the combined and market valued at $40.2 billion, where hams hold about 40% share of processed pork applications. For 2025, production stability is expected globally, with benefits from lower input costs offsetting localized African Swine Fever (ASF) resurgences, such as in parts of where herd adjustments have tempered output. U.S. forecasts project a 2.7% production uptick alongside 4% higher hog prices, while Brazil's export momentum continues despite uncertainties. Supply chain advancements, including scale efficiencies and technological integration, have contributed to declining per-unit production costs since 2000, enabling expanded despite volatility. In 2025, the global pork market has benefited from declining feed costs, projected to be 8% lower than in 2024 due to favorable corn and harvests, enhancing producer margins to an average of $20 per head in the U.S.. Adoption of for real-time monitoring in pig barns has accelerated, with AI systems detecting health issues via behavior analysis and cough detection, optimizing feed use and reducing disease losses in operations from to . These efficiencies support scale advantages, where larger farms achieve higher technical efficiency—often exceeding 80% in output per input—compared to smaller operations, as evidenced by analyses of commercial pig fattening data showing productivity gains from expanded herd sizes. Persistent disease pressures, including African Swine Fever (ASF) in and Porcine Reproductive and Respiratory Syndrome (PRRS) outbreaks in the U.S., have led to downward revisions in production forecasts; for instance, USDA reduced U.S. 2025 pork output projections amid PRRS impacts, while 's endemic ASF is expected to curb national production growth. Geopolitical trade disruptions exacerbate these, with 's retaliatory tariffs squeezing exports—where absorbs 25% of volume—and cancellations of 12,000 tons of U.S. shipments, alongside potential U.S. reciprocal tariffs under heightened policy scrutiny, inflating costs and redirecting flows to markets like . Claims of competition from plant-based proteins overlook pork's superior nutritional density, providing 27.6 g of per 100 g—higher quality than plant sources due to balanced essential amino acids—alongside bioavailable iron and absent or less efficient in and grains. Regulatory challenges, including stricter environmental controls on and restrictions, further strain margins by raising compliance costs 10-15% in regions like the , though empirical data affirm that pork's efficiency in converting feed to high-density sustains demand amid these pressures.

Uses and Products

Food and Nutrition

Pork provides high-quality , typically comprising 20-25% of its fresh weight, supporting muscle synthesis and repair due to essential like that stimulate muscle protein synthesis post-exercise. A 2025 study found that consuming lean after workouts enhanced muscle growth more effectively than high-fat variants, even at equivalent protein levels, by optimizing recovery and reducing . Additionally, 's protein aids in maintaining muscle mass and function, particularly in aging populations or athletes, countering through regular intake as part of an active lifestyle. Pork is notably rich in B-vitamins, including (vitamin B1) and niacin (vitamin B3), with pork muscle containing higher levels than many other meats, contributing up to 31% of daily needs in moderate servings. These vitamins exhibit high , facilitating and nerve function. Minerals such as , iron, , and are also abundant, with pork providing bioavailable heme iron for oxygen transport and for defense. Lean cuts, like tenderloin or , offer protein-to-fat ratios comparable to skinless , with about 25 grams of protein and 4 grams of fat per 3-ounce serving, making them suitable for low-fat diets.
Nutrient (per 100g cooked lean )Amount% Daily Value (approx.)
Protein27g54%
(B1)0.9mg75%
Niacin (B3)5mg31%
2.4mg22%
45µg82%
3g15%
Data adapted from USDA nutrient databases; values vary by cut and preparation. Global pork consumption averages around 15 kilograms annually, accounting for about 34% of total intake worldwide, with higher rates in regions like the (35.5 kg) and (30.4 kg). While contains saturated fats (35-40% of total fat content), pasture-raised varieties balance this with elevated omega-3 fatty acids from diets, improving omega-6:3 ratios and potentially reducing compared to grain-fed . Food safety concerns include trichinellosis from Trichinella parasites, though commercial pork in regulated systems like the U.S. shows near-zero prevalence due to biosecurity measures, with risks minimized by cooking to an internal temperature of 71°C (160°F). Empirical data indicate modern production eliminates this as a significant threat for properly handled pork, emphasizing thorough cooking over avoidance.

By-Products and Industrial Uses

Pig hides, comprising about 10-15% of a slaughtered pig's weight, are processed into suitable for gloves, , and specialty due to their flexibility and pattern. In the United States, over 1 million pigskins were exported for leather production in 2021, contributing to an industry valued at more than $1.4 billion when including semi-processed goods. Globally, pig leather represents a minor but consistent by-product stream, with hides often split for upper and lower layers to maximize utility in and accessories. Rendered pig fat, known as , is saponified to produce soaps and utilized in lubricants; historically, it served as a source of glycerin for in explosives during the 19th and early 20th centuries. Pig bones and connective tissues yield for industrial glues, explosives stabilizers, and matches, with porcine sources accounting for a significant portion of non-edible gelatin production. Ground pig bones form , providing 2-14% and trace minerals to enhance and crop yields, particularly in ; porcine-derived variants are processed via steaming to ensure sterility. harvested from pig necks and backs, prized for their taper and resilience, are fashioned into premium paintbrushes and industrial cleaning tools, with hog bristle comprising a key filament in oil-based applications. Pig manure, often co-digested with other organics, generates through ; as of April 2021, 45 U.S. systems handling swine waste produced equivalent to offsetting 650,000 metric tons of CO2e annually, while yielding for . This process captures that would otherwise contribute to greenhouse emissions, with biogas yields averaging 20-36 cubic meters per of waste depending on system efficiency.

Biomedical Applications

Pigs have been utilized in biomedical research and due to physiological similarities with s, including comparable organ sizes, cardiovascular systems, and metabolic pathways. Their pancreases served as a primary source for insulin production starting in 1921, when and Charles Best extracted the hormone from bovine and porcine sources to treat ; porcine insulin remained a staple until recombinant human insulin emerged in the . Similarly, porcine heart valves, decellularized and treated to reduce , have been implanted in over 100,000 human patients annually since the 1960s for treating , offering a biocompatible alternative to mechanical valves that avoids lifelong anticoagulation. Pigs serve as valuable animal models for studying diseases, particularly those involving the respiratory, digestive, and neurological systems. Genetically modified pigs replicate conditions like through targeted mutations in the CFTR gene, enabling research into and therapeutic interventions that translate to trials. Their , structurally akin to , is used to model , burns, and dermatological disorders, with porcine xenografts applied in temporary coverage for severe burns since the 1970s. Advances in have accelerated with CRISPR-edited pigs, addressing hyperacute rejection via knockouts of alpha-gal epitopes and insertions of complement regulators. In , eGenesis reported survival of gene-edited porcine kidneys in brain-dead recipients for up to 77 days, incorporating edits to 10 genes including GGTA1, CMAH, B4GALNT2, and transgenes like CD46 and THBD. By early 2025, United Therapeutics' UKidney, a 10-gene-modified porcine , underwent clinical s in living humans, with initial data showing reduced antibody-mediated rejection compared to prior unmodified grafts; a liver in similarly sustained function for 10 days in a brain-dead recipient. These developments, building on a 2022 pig-to- heart transplant that extended life by two months before rejection, highlight pigs' potential to alleviate organ shortages, though long-term viability and risks from porcine endogenous retroviruses persist as challenges requiring further immunosuppression refinements.

Impacts of Pig Husbandry

Public Health Considerations

Pigs serve as reservoirs for influenza A viruses, including subtypes that can reassort and transmit to humans, as seen in sporadic variant influenza infections reported annually, primarily among those with direct contact such as agricultural workers. The 2009 H1N1 pandemic originated from a triple reassortant swine influenza virus, highlighting pigs' role as a "mixing vessel" for avian, human, and porcine strains that pose pandemic risks. Human infections with swine-origin viruses remain rare but underscore the need for biosecurity in pig handling to prevent interspecies jumps. Foodborne pathogens in pork, such as Salmonella, E. coli, and parasites like Trichinella spiralis, pose risks if meat is undercooked or cross-contaminated during handling. Cooking whole pork cuts to an internal temperature of 145°F (63°C) followed by a 3-minute rest, or ground pork to 160°F (71°C), effectively kills these pathogens by denaturing proteins and disrupting cellular structures essential for microbial survival. Such thermal processing achieves near-complete elimination of viable bacteria and parasites, reducing outbreak risks when combined with proper sanitation. Antimicrobial use in production, accounting for approximately 40% of medically important administered to U.S. animals, has contributed to the selection and dissemination of resistant that can transfer to human pathogens via chains or environmental pathways. Empirical data from the demonstrate that reducing use in by 54% from 2009 to 2016, through improved husbandry and veterinary oversight rather than outright bans, lowered resistance without compromising animal health or productivity. While bans on growth-promoting antibiotics in regions like the have yielded mixed results, with some increases in animal disease incidence, targeted —focusing on therapeutic needs and alternatives—balances control in herds against resistance , as overuse for non-therapeutic purposes amplifies selective without proportional benefits. Genomic sequencing enhances of outbreaks linked to pigs, enabling differentiation of strains to pinpoint sources, as in cases of Choleraesuis where whole-genome analysis linked clones from swine, wildlife, and human infections. This approach, applied to bacterial and viral pathogens, supports rapid public health responses by reconstructing transmission chains and informing interventions, such as targeted culls or recalls, with higher resolution than traditional serotyping.

Environmental Effects

Pig farming contributes to primarily through , management, and feed production, with total emissions averaging 6-7 kg CO₂e per kg of produced, significantly lower than beef's 50-100 kg CO₂e per kg due to pigs' digestion avoiding production. from storage accounts for a substantial portion, but strategies like covered anaerobic digesters can capture for energy, reducing net emissions by up to 80% in some systems. Pigs exhibit high feed conversion efficiency, requiring approximately 3-4 kg of feed per kg of live , compared to 6-10 kg or more for , enabling lower overall resource use per unit of protein output. This efficiency stems from pigs' ability to utilize diverse feeds, including by-products, though a large share (up to 80% of global soy) goes to , indirectly linking production to in regions like the Amazon and . High-yield soy cultivation and alternatives like food waste incorporation can offset land demands, potentially reducing soy-related acreage by 25-30% in scenarios integrating feeding. Manure from pigs serves as a valuable source of and for crop fertilization, recycling up to 90% of these nutrients when properly separated and applied, enhancing without synthetic inputs. However, excess application risks ; lagoon systems, common in intensive operations, stabilize for controlled release, with treatments like aluminum precipitating to cut soluble runoff by 70-90%, thereby mitigating algal blooms in waterways. Intensification of pig production has substantially decreased land use intensity, with modern systems requiring 75% less cropland per kg of than traditional extensive methods, as higher stocking densities and precise minimize and feed expansion. This shift, while concentrating , allows for targeted environmental controls absent in dispersed farming, though it demands vigilant management to prevent localized hotspots.

Animal Welfare and Ethical Debates

Intensive pig husbandry systems prioritize efficient growth while addressing welfare through practices informed by empirical data on space, behavior, and health outcomes. Studies indicate that space allowances exceeding 0.80 m² per pig in grow-to-finish phases support optimal growth performance and production efficiency, with lower densities potentially increasing aggression but sufficient provision meeting basic physiological needs for resting and movement. Tail docking, performed on most piglets in commercial operations, reduces the incidence of severe tail biting lesions by approximately 50%, mitigating a behavioral vice exacerbated by confinement and poor enrichment, though it imposes acute pain and does not fully eliminate the problem. Environmental enrichment, such as substrates or manipulable objects, demonstrably lowers stereotypic behaviors like bar-biting and sham chewing, while decreasing aggression and fear responses in pigs, as evidenced by reduced fighting and shorter latencies to objects in enriched groups. These interventions align with pigs' exploratory and rooting instincts, improving welfare metrics without compromising productivity, though implementation varies by system. Welfare certifications like (AWA) and Global Animal Partnership (GAP) enforce standards for natural behaviors, group housing, and enrichment, aiming to exceed basic regulatory minima, yet critics argue some schemes permit crates or insufficient outdoor access, questioning their rigor against industry pressures. Ethical debates center on reconciling human nutritional benefits from affordable pork protein—providing essential efficiently—with verifiable animal suffering claims, where proponents emphasize that intensive systems enable global amid rising demand, while opponents highlight confinement-induced vices. Critiques of welfare advocacy note risks of , wherein human-like attributions overlook pigs' natural social hierarchies involving dominance and , potentially misinterpreting adaptive behaviors as distress; empirical observations confirm stable hierarchies reduce overall conflict in group-housed pigs when space and resources suffice. Thus, causal assessments prioritize interventions yielding measurable reductions in lesions or over idealized "natural" conditions that may elevate disease or injury risks in practice.

Cultural and Religious Significance

In , the consumption of is prohibited by kosher dietary laws outlined in Leviticus 11:7-8 and Deuteronomy 14:8, which classify pigs as unclean animals because they possess cloven hooves but do not chew the cud. This , rooted in ancient Israelite practices distinguishing them from neighboring cultures that consumed , symbolizes ritual purity and separation from idolatry, as pigs were associated with Canaanite and Philistine rituals. Islam similarly forbids pork, with the Quran explicitly stating in Surah Al-Baqarah 2:173 that swine flesh is impure and prohibited except in cases of necessity to avoid starvation. This ruling reinforces monotheistic purity laws, echoing Jewish traditions while extending to all Muslims regardless of context, and has historically fostered communal identity amid diverse food practices. In , prohibitions were superseded by teachings, particularly Peter's vision in Acts 10:9-16 declaring all foods clean, enabling widespread consumption among adherents. Certain denominations, such as Seventh-day Adventists, retain avoidance based on interpretations of Leviticus, but most view the restriction as ceremonial rather than enduring moral law. Hinduism presents a dual view: the boar-headed Varaha, an avatar of who rescued the earth from cosmic waters in texts like the , elevates pigs to divine status symbolizing protection and fertility. Yet, cultural norms often deem pigs impure due to scavenging habits, leading many Hindus to abstain from as a mark of ritual cleanliness, though no universal scriptural ban exists. In , pigs hold positive symbolism as the twelfth zodiac animal, representing , , and diligence; families historically amassed pig herds as status symbols, with zodiac lore attributing traits like honesty and generosity to those born in Pig years (e.g., 1959, 1971, 1983). This contrasts with Western associations of greed, deriving from like the "greedy as a pig" . Ancient mythologies featured pigs in sacrifices and deities: in , swine offerings to honored agricultural cycles, reflecting pigs' fertility; Egyptian rites linked sows to for renewal. Pre-Christian European traditions sacrificed pigs to mother goddesses for abundance, underscoring their role in fertility cults before Christian assimilation diminished such practices.

References

  1. https://pubchem.ncbi.nlm.nih.gov/taxonomy/9825
  2. https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=9825
  3. https://pmc.ncbi.nlm.nih.gov/articles/PMC1461048/
  4. https://anthropology.dartmouth.edu/news/2025/06/pigs-were-domesticated-wild-boars-south-china
  5. https://www.thoughtco.com/the-domestication-of-pigs-170665
  6. https://www.cambridge.org/core/journals/nutrition-research-reviews/article/critical-review-evaluating-the-pig-as-a-model-for-human-nutritional-physiology/0710FD9CEFAEC32B730A5CA9B06B511A
  7. https://pmc.ncbi.nlm.nih.gov/articles/PMC11016693/
  8. https://pmc.ncbi.nlm.nih.gov/articles/PMC7152257/
  9. https://www.cambridge.org/core/books/ecology-conservation-and-management-of-wild-pigs-and-peccaries/evolutionary-relationships-and-taxonomy-of-suidae-and-tayassuidae/BDB184D58924C6F7993E7D7CA52FE59C
  10. https://journals.biologists.com/jeb/article/223/15/jeb223974/224493/Disruption-of-thermogenic-UCP1-predated-the
  11. https://pubmed.ncbi.nlm.nih.gov/26526544/
  12. https://www.sciencedirect.com/science/article/abs/pii/S0277379118302701
  13. https://www.researchgate.net/publication/283481123_The_Evolution_of_Suidae
  14. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/suidae
  15. https://www.researchgate.net/publication/236898646_Family_Suidae_Pigs
  16. https://www.gbif.org/species/113392271
  17. https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.105520/Sus_scrofa
  18. https://www.inaturalist.org/taxa/42126-Sus
  19. https://pmc.ncbi.nlm.nih.gov/articles/PMC7444817/
  20. https://pmc.ncbi.nlm.nih.gov/articles/PMC8986821/
  21. http://www.macroevolution.net/pig-hybrids.html
  22. https://wildlife.org/genetics-help-combat-illegal-movement-of-feral-swine/
  23. https://www.researchgate.net/publication/369770944_Taxonomy_and_History_of_Wild_Pigs_in_the_United_States
  24. https://www.pnas.org/doi/10.1073/pnas.2507123122
  25. https://www.cambridge.org/core/journals/antiquity/article/pig-domestication-in-ancient-china/013BDB805CC285C0439CE77A86AA7C63
  26. https://www.nature.com/articles/s41598-017-06056-8
  27. https://academic.oup.com/mbe/article/42/9/msaf214/8262945
  28. https://www.sciencedirect.com/science/article/pii/S1673852721003684
  29. https://pmc.ncbi.nlm.nih.gov/articles/PMC9495052/
  30. https://pmc.ncbi.nlm.nih.gov/articles/PMC3070695/
  31. https://www.intechopen.com/chapters/64922
  32. https://www.pnas.org/doi/10.1073/pnas.2511400122
  33. https://www.sciencedirect.com/science/article/abs/pii/S0305440322000486
  34. https://www.evolutio.art/pig-anatomy-18-pvc
  35. https://www.visiblebody.com/blog/visible-biologys-visual-guide-to-pig-anatomy
  36. https://phys.org/news/2011-05-wallowing-mud-temperature.html
  37. https://pmc.ncbi.nlm.nih.gov/articles/PMC9751486/
  38. https://www.livescience.com/32118-do-pigs-sweat.html
  39. https://svineproduktion.dk/-/media/PDF/Services/Undervisningsmateriale/Laerebog_fysiologi/Chapter-5.ashx
  40. https://pmc.ncbi.nlm.nih.gov/articles/PMC9316789/
  41. https://open.oregonstate.education/animalnutrition/chapter/chapter-2/
  42. https://www.nature.com/articles/s41598-017-18775-z
  43. https://www.sciencedirect.com/science/article/pii/S002231662210948X
  44. https://www.dimensions.com/element/wild-boar
  45. https://aaacwildliferemoval.com/blog/boars/how-big-is-a-full-grown-wild-boar/
  46. https://sti.srs.gov/fulltext/SRNL-RP-2009-00869.pdf
  47. https://www.aphis.usda.gov/operational-wildlife-activities/feral-swine/identification
  48. https://encyclopedia.pub/entry/31811
  49. https://customcreationswine.weebly.com/full-size-heritage-swine-info.html
  50. http://bigpictureagriculture.blogspot.com/2015/11/fourteen-heritage-pig-breeds.html
  51. https://pmc.ncbi.nlm.nih.gov/articles/PMC9499681/
  52. https://www.nature.com/articles/srep27534
  53. https://www.sciencedaily.com/releases/2009/01/090116073327.htm
  54. https://www.reddit.com/r/zoology/comments/1dqsjik/why_are_domestic_pigs_pink/
  55. https://www.osti.gov/servlets/purl/1776687
  56. https://extension.psu.edu/reproduction-in-swine-understanding-the-estrous-cycle-for-herd-management/
  57. https://www.merckvetmanual.com/management-and-nutrition/management-of-reproduction-pigs/breeding-management-of-pigs
  58. https://www.merckvetmanual.com/multimedia/table/features-of-the-reproductive-cycle
  59. https://pmc.ncbi.nlm.nih.gov/articles/PMC6067529/
  60. https://porkcheckoff.org/pork-branding/facts-statistics/life-cycle-of-a-market-pig/
  61. https://www.quora.com/How-long-is-pregnancy-term-for-a-pig-How-many-piglets-on-average-do-they-give-birth-to
  62. https://pmc.ncbi.nlm.nih.gov/articles/PMC11240334/
  63. https://pmc.ncbi.nlm.nih.gov/articles/PMC9951909/
  64. https://jasbsci.biomedcentral.com/articles/10.1186/s40104-022-00687-2
  65. https://pmc.ncbi.nlm.nih.gov/articles/PMC11100174/
  66. https://academic.oup.com/biolreprod/article/75/5/792/2629067
  67. https://pubmed.ncbi.nlm.nih.gov/26723133/
  68. https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2022.1067878/full
  69. https://www.sciencedirect.com/science/article/abs/pii/S0018506X07000682
  70. https://pmc.ncbi.nlm.nih.gov/articles/PMC4647089/
  71. https://www.researchgate.net/publication/285974403_The_development_of_suckling_frequency_in_pigs_from_birth_to_weaning_of_their_piglets_A_sociobiological_approach
  72. https://www.wellbeingintlstudiesrepository.org/cgi/viewcontent.cgi?article=1001&context=feebeh
  73. https://www.canr.msu.edu/news/unwavering-loyalty-piglet-devotion-to-the-chosen-sow-teat
  74. https://www.merckvetmanual.com/behavior/behavior-of-production-animals/behavior-of-swine
  75. https://aab.copernicus.org/articles/68/263/2025/
  76. https://porkgateway.org/resource/how-does-weaning-age-affect-the-welfare-of-the-nursery-pig/
  77. https://www.sciencedirect.com/science/article/pii/0168159189900063
  78. https://www.naturalremedy.com/blog/importance-of-weaning-in-pigs/
  79. https://americankunekunepigsociety.org/weaning-piglets/
  80. https://rifle-shooter.com/rifles/wild-boar-social-structure-and-best-management-practises/
  81. https://nri.tamu.edu/publications/peer-reviewed-publications/2022/genomic-tools-reveal-complex-social-organization-of-an-invasive-large-mammal-sus-scrofa/
  82. https://www.nature.com/articles/s41598-022-07174-8
  83. https://www.wellbeingintlstudiesrepository.org/cgi/viewcontent.cgi?article=1001&context=mammal
  84. https://ri.conicet.gov.ar/bitstream/handle/11336/8024/CONICET_Digital_Nro.10551.pdf?sequence=1
  85. https://www.nature.com/articles/s41598-023-48139-9
  86. https://tpwd.texas.gov/huntwild/wild/nuisance/feral_hogs/
  87. https://www.researchgate.net/publication/235771627_Food_habits_and_impact_of_rooting_behaviour_of_the_invasive_wild_boar_Sus_scrofa_in_a_protected_area_of_the_Monte_Desert_Argentina
  88. https://pmc.ncbi.nlm.nih.gov/articles/PMC10519948/
  89. https://www.researchgate.net/publication/257018050_Review_of_wallowing_in_pigs_Description_of_the_behaviour_and_its_motivational_basis
  90. https://www.researchgate.net/figure/Sleep-and-Circadian-Rhythms-Sleep-Wake-graph-showing-that-pigs-tend-to-fall-asleep_fig7_350238122
  91. https://www.sciencedirect.com/science/article/pii/0031938486902350
  92. https://pmc.ncbi.nlm.nih.gov/articles/PMC10913826/
  93. https://www.dogster.com/lifestyle/are-pigs-smarter-than-dogs
  94. https://betweencommunitynews.town.news/g/between-ga/n/284453/interesting-science-research-shows-pigs-outperform-dogs-intelligence-rivaling
  95. https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2021.631755/full
  96. https://www.thedodo.com/pig-solves-puzzle-video-1555892494.html
  97. https://www.sciencedirect.com/science/article/pii/S0003347209003571
  98. https://pmc.ncbi.nlm.nih.gov/articles/PMC11504952/
  99. https://pmc.ncbi.nlm.nih.gov/articles/PMC4910673/
  100. https://pubmed.ncbi.nlm.nih.gov/11179556/
  101. https://bmcgenomics.biomedcentral.com/articles/10.1186/s12864-025-11281-x
  102. https://www.sciencedirect.com/science/article/pii/S1751731124002507
  103. https://pmc.ncbi.nlm.nih.gov/articles/PMC4027392/
  104. https://pubmed.ncbi.nlm.nih.gov/2272932/
  105. https://anatomypubs.onlinelibrary.wiley.com/doi/full/10.1002/ar.23095
  106. https://anrcatalog.ucanr.edu/pdf/8479.pdf
  107. https://dspace.library.uu.nl/bitstream/handle/1874/414402/3_s2.0_B9780128094686000395_main.pdf?sequence=1
  108. https://www.aasv.org/shap/issues/v28n5/v28n5p244.html
  109. https://www.thepigsite.com/disease-guide/porcine-reproductive-respiratory-syndrome-prrs
  110. https://www.woah.org/en/disease/porcine-reproductive-and-respiratory-syndrome/
  111. https://www.merckvetmanual.com/infectious-diseases/foot-and-mouth-disease/foot-and-mouth-disease-in-animals
  112. https://www.woah.org/en/disease/foot-and-mouth-disease/
  113. https://webhost-dev.cvm.iastate.edu/swine-disease-manual/index-of-diseases/foot-and-mouth-disease-fmd/
  114. https://www.thepigsite.com/disease-guide/erysipelas-diamond-lesion
  115. https://www.vetspecialists.com/vet-blog-landing/animal-health-articles/2023/01/17/erysipelas-in-swine
  116. https://webhost-dev.cvm.iastate.edu/swine-disease-manual/index-of-diseases/erysipelas/
  117. https://www.aphis.usda.gov/livestock-poultry-disease/swine/swine-brucellosis
  118. https://pmc.ncbi.nlm.nih.gov/articles/PMC6042558/
  119. https://www.sciencedirect.com/science/article/abs/pii/S0378113513001399
  120. https://wwwnc.cdc.gov/eid/article/31/1/24-0401_article
  121. https://pubmed.ncbi.nlm.nih.gov/39714396/
  122. https://www.merckvetmanual.com/digestive-system/gastrointestinal-parasites-of-pigs/ascaris-suum-in-pigs
  123. https://www.cdc.gov/sth/about/about-ascaris-in-pigs.html
  124. https://webhost-dev.cvm.iastate.edu/swine-disease-manual/index-of-diseases/roundworm-infection-ascariasis/
  125. https://www.merckvetmanual.com/integumentary-system/mange/mange-in-pigs
  126. https://www.nadis.org.uk/disease-a-z/pigs/sarcoptic-mange/
  127. https://pmc.ncbi.nlm.nih.gov/articles/PMC4675569/
  128. https://www.pig333.com/pig-diseases/mange_64
  129. https://www.thepigsite.com/articles/rodent-control-in-livestock-and-poultry-facilities
  130. https://porkgateway.org/resource/controlling-rats-and-mice-in-swine-facilities/
  131. https://www.sciencedirect.com/science/article/pii/S0167587724001144
  132. https://www.thepigsite.com/disease-and-welfare/managing-disease/airborne-transmission-and-other-methods
  133. https://pmc.ncbi.nlm.nih.gov/articles/PMC10251848/
  134. https://www.nadis.org.uk/disease-a-z/pigs/worms/
  135. https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2025.9436
  136. https://www.swinehealth.org/global-disease-surveillance-reports/
  137. https://www.woah.org/app/uploads/2025/10/asf-report-69.pdf
  138. https://www.fao.org/animal-health/situation-updates/asf-in-asia-pacific/en
  139. https://pigua.info/en/post/news-of-ukraine-and-world/asf-in-latvia-20000-pigs-to-be-destroyed-at-sia-baltic-pork-farm
  140. https://eng.lsm.lv/article/society/environment/09.09.2025-african-swine-fever-risk-in-latvia-particularly-high.a613679/
  141. https://www.woah.org/en/disease/african-swine-fever/
  142. https://nationalpigassociation.co.uk/asf-outbreaks-in-estonia-and-latvia-result-in-50000-pigs-being-culled/
  143. https://www.sciencedirect.com/science/article/pii/S0167587724002393
  144. https://www.theguardian.com/science/2025/oct/22/scientists-create-pigs-resistant-to-classical-swine-fever-gene-editing
  145. https://www.newscientist.com/article/2500908-gene-edited-pigs-resistant-to-swine-fever-could-boost-animal-welfare/
  146. https://www.ilri.org/african-swine-fever
  147. https://edinburgh-infectious-diseases.ed.ac.uk/news/latest-news/gene-edited-pigs-resistant-to-deadly-viral-disease-developed
  148. https://pmc.ncbi.nlm.nih.gov/articles/PMC3603306/
  149. https://www.academia.edu/32294247/Again_on_pigs_in_Ancient_Europe_The_Fennic_connection
  150. https://www.researchgate.net/publication/316521163_The_Prehistory_of_the_Silk_Road
  151. https://pmc.ncbi.nlm.nih.gov/articles/PMC5043315/
  152. https://www.laphamsquarterly.org/roundtable/ubiquitous-medieval-pigs
  153. https://www.cambridge.org/core/journals/antiquity/article/pork-for-pilgrims-livestock-breeding-and-meat-consumption-at-medieval-banganarti-nubia/A4A732A7C8D9E56CE9B9DA25562F3116
  154. https://www.mdpi.com/2571-9408/7/2/49
  155. https://www.intechopen.com/chapters/81768
  156. https://www.fao.org/4/ah759e/AH759E10.htm
  157. https://www.researchgate.net/publication/283554767_History_and_culture_of_pig_breeding_and_housing_3rd_comm_Pig_breeding_and_housing_in_Germany_from_1650_to_1900
  158. https://www.khanacademy.org/humanities/us-history/precontact-and-early-colonial-era/old-and-new-worlds-collide/a/the-columbian-exchange-ka
  159. https://www.bzhumdrum.com/pig/introduction.html
  160. https://www.theproductiveteacher.com/columbian-exchange-horses-pigs-and-cattle-for-ap-world-history
  161. https://exploration.marinersmuseum.org/subject/hernando-de-soto/
  162. https://www.reddit.com/r/todayilearned/comments/703wak/til_hernando_de_soto_brought_13_pigs_to_north/
  163. https://www.whatismissing.org/content/hernando-de-soto-introduces-wild-boar-to-america
  164. https://www.bzhumdrum.com/pig/chapter3.html
  165. https://www.researchgate.net/publication/326070199_Biological_invasion_of_wild_boar_and_feral_pigs_sus_scrofa_Suidae_in_south_america_Review_and_mapping_with_implications_for_conservation_of_peccaries_Tayassuidae
  166. https://pmc.ncbi.nlm.nih.gov/articles/PMC3607178/
  167. https://www.austinchronicle.com/food/a-history-of-pigs-in-america-11744331/
  168. https://texaspork.org/history-of-pork/
  169. https://tpwd.[texas](/page/Texas).gov/huntwild/wild/nuisance/feral_hogs/
  170. https://www.aphis.usda.gov/operational-wildlife-activities/feral-swine
  171. https://www.forbes.com/sites/brianbushard/2024/06/15/feral-swine-bomb-explained-why-wild-hogs-in-35-states-have-scientists-worried/
  172. https://a-z-animals.com/blog/wild-hog-feral-hog-wild-boar-population-by-state/
  173. https://www.aphis.usda.gov/sites/default/files/fsc-feral-swine-impacts-tes.pdf
  174. https://nri.tamu.edu/news/2019/may/wild-pig-wars-controversy-over-hunting-trapping/
  175. https://www.nationalhogfarmer.com/livestock-management/finally-feral-pig-control-
  176. https://jasbsci.biomedcentral.com/articles/10.1186/s40104-015-0031-2
  177. https://www.sciencedirect.com/science/article/abs/pii/S0167587798000944
  178. https://www.scielo.br/j/rbz/a/NC94QQqSXFkPVz9qhbx3pfS/
  179. https://pmc.ncbi.nlm.nih.gov/articles/PMC1817683/
  180. https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2024.1450649/full
  181. https://ourworldindata.org/antibiotics-livestock
  182. https://www.choicesmagazine.org/UserFiles/file/cmsarticle_404.pdf
  183. https://www.nature.com/articles/s41598-023-29480-5
  184. https://pmc.ncbi.nlm.nih.gov/articles/PMC7433918/
  185. https://nationalswine.com/about/breeds/about-yorkshire.php
  186. https://www.thepigsite.com/breeds/american-yorkshire
  187. https://vanderosefarms.com/decoding-the-secrets-of-the-heritage-breed-duroc-pig/
  188. https://www.usfoods.com/great-food/food-trends/what-duroc-pork.html
  189. https://porkcheckoff.org/pork-branding/facts-statistics/major-swine-breeds/
  190. https://ecofarmingdaily.com/raise-healthy-livestock/pigs/practical-pork/
  191. https://www.tenderbelly.com/blogs/foodie/the-biz-on-heritage-breed-pigs
  192. https://www.themeateater.com/wild-and-whole/homesteading/what-pig-breed-is-right-for-your-homestead
  193. https://pmc.ncbi.nlm.nih.gov/articles/PMC7070372/
  194. https://cabiagbio.biomedcentral.com/articles/10.1186/s43170-022-00073-y
  195. https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2012.00281/full
  196. https://pmc.ncbi.nlm.nih.gov/articles/PMC6007440/
  197. https://academic.oup.com/g3journal/article/12/7/jkac118/6585340
  198. https://swine.extension.org/inbreeding-in-swine/
  199. https://vet.ed.ac.uk/roslin/news-events/2025/pigs-developed-to-be-resistant-to-deadly-virus
  200. https://www.ft.com/content/dd389d6e-6fde-40f1-becc-cc2c165426d7
  201. https://www.avma.org/news/fda-approves-gene-editing-tech-creating-prrs-resistant-pigs
  202. https://www.nationalhogfarmer.com/livestock-management/fda-approves-prrs-resistant-pig
  203. https://www.nature.com/articles/s41587-025-02716-7
  204. https://geneticliteracyproject.org/2025/09/09/crispr-pork-u-s-approves-first-gene-edited-pigs-for-consumption/
  205. https://www.science.org/doi/10.1126/science.2499927
  206. https://pmc.ncbi.nlm.nih.gov/articles/PMC3522184/
  207. https://www.mdpi.com/2076-2615/15/3/422
  208. https://pmc.ncbi.nlm.nih.gov/articles/PMC11892312/
  209. https://gsejournal.biomedcentral.com/articles/10.1186/s12711-025-00957-3
  210. https://www.porkbusiness.com/news/hog-production/artificial-intelligence-future-swine-genetics
  211. https://jasbsci.biomedcentral.com/articles/10.1186/s40104-022-00708-0
  212. https://www.prrsresistantpig.com/earning-regulatory-approval/
  213. https://nationalpigassociation.co.uk/npa-welcomes-landmark-us-gene-editing-decision/
  214. https://www.fas.usda.gov/data/production/commodity/0113000
  215. https://paradigmfutures.net/a/education/top-pork-producing/
  216. https://www.iowafarmbureau.com/Article/World-Pork-Trade
  217. https://www.worldstopexports.com/pork-exports-by-country/
  218. https://www.porkbusiness.com/news/industry/brazils-pork-exports-expected-grow-5-2025-despite-global-trade-uncertainties
  219. https://americanporkclub.com/Home/news/news-usa/usda-pork-production-forecast-2024
  220. https://www.indexbox.io/blog/bacon-and-ham-world-market-overview-2024-2/
  221. https://www.mordorintelligence.com/industry-reports/global-pork-meat-market
  222. https://www.rabobank.com/knowledge/q011420206-global-pork-quarterly-q3-2025-production-benefits-from-lower-costs-while-trade-faces-geopolitical-challenges
  223. https://www.porkbusiness.com/markets/market-news/pork-industry-outlook-improving-2025-cook-says
  224. https://ers.usda.gov/sites/default/files/_laserfiche/publications/104437/ERR-308.pdf
  225. https://ag.purdue.edu/commercialag/home/resource/2025/06/prospects-for-swine-feed-costs-in-the-second-half-of-2025/
  226. https://www.sfntoday.com/2025/10/22/pork-producers-return-to-profitability-in-2025/
  227. https://pigax.com/en/blog/piggery/is-ai-changing-pig-farming-heres-what-every-farmer-should-know
  228. https://www.livestockresearch.ca/article/artificial_intelligence_tech_emerging_slowly_in_pork_industry
  229. https://www.nature.com/articles/s41598-024-70900-x
  230. https://www.nationalhogfarmer.com/market-news/usda-cuts-2025-pork-production-forecast-amid-prrs-outbreaks
  231. https://www.tridge.com/news/chinas-pork-production-to-decline-by-2025-vsulxb
  232. https://www.reuters.com/world/china/chinas-retaliatory-tariffs-squeeze-eu-pork-producers-2025-09-10/
  233. https://www.usimportdata.com/blogs/china-cancels-us-pork-imports-2025-impact-on-us-pork-imports-by-country
  234. https://advances.nutrition.org/article/S2161-8313%2824%2900047-4/fulltext
  235. https://www.verywellhealth.com/plant-protein-vs-animal-protein-8781023
  236. https://www.sciencedirect.com/science/article/pii/S1751731125001302
  237. https://www.tridge.com/news/5-major-challenges-in-2025-for-the-global-an-ikmyxj
  238. https://www.healthline.com/nutrition/foods/pork
  239. https://pmc.ncbi.nlm.nih.gov/articles/PMC11202857/
  240. https://www.sciencedaily.com/releases/2025/10/251015032318.htm
  241. https://www.webmd.com/diet/pork-good-for-you
  242. https://www.sciencedirect.com/science/article/abs/pii/S0271531711001771
  243. https://www.sciencedirect.com/science/article/abs/pii/S0308814696003044
  244. https://cosmoappliances.com/nutritional-comparison-of-different-meats-chicken-beef-and-pork/
  245. https://www.ars.usda.gov/is/np/NutritiveValueofFoods/NutritiveValueofFoods.pdf
  246. https://worldpopulationreview.com/country-rankings/pork-consumption-by-country
  247. https://pmc.ncbi.nlm.nih.gov/articles/PMC4693156/
  248. https://practicalfarmers.org/research/fatty-acid-comparisons-of-grain-and-forage-fed-pork/
  249. https://www.ars.usda.gov/news-events/news/research-news/2024/usda-research-documents-absence-of-trichinella-infection-in-commercial-pigs/
  250. https://my.clevelandclinic.org/health/diseases/7142-trichinosis
  251. https://pmc.ncbi.nlm.nih.gov/articles/PMC9356189/
  252. https://www.usleather.org/press/US_Hide_Skin_Leather_Industry_2021_Year_End_Data_2022_Projections
  253. https://www.leathernaturally.org/resources/fact-sheets/faq-the-real-connection-between-leather-and-the-me/
  254. https://nwedible.com/would-you-rub-pork-fat-on-your-face/
  255. https://www.aocs.org/resource/animal-fats/
  256. https://www.compostwerks.com/organics/soil-amendments/product/50-bone-meal-50-pound-bag
  257. https://www.widdops.com/animal-hair/
  258. https://www.epa.gov/agstar/anaerobic-digestion-swine-farms
  259. https://www.sciencedirect.com/science/article/abs/pii/S0960148114002547
  260. https://www.cdc.gov/swine-flu/variant-flu-in-humans/index.html
  261. https://pmc.ncbi.nlm.nih.gov/articles/PMC2702078/
  262. https://www.ecdc.europa.eu/en/swine-influenza/factsheet
  263. https://www.foodsafety.gov/food-safety-charts/safe-minimum-internal-temperatures
  264. https://www.cidrap.umn.edu/foodborne-disease/usda-145-degrees-safe-temp-pork
  265. https://www.fooddocs.com/food-safety-templates/pork-temperature-chart
  266. https://clear.ucdavis.edu/explainers/antibiotics-and-antimicrobial-resistance
  267. https://theconversation.com/antibiotic-resistance-how-drug-misuse-in-livestock-farming-is-a-problem-for-human-health-141911
  268. https://www.sciencedirect.com/science/article/pii/S0378113521003059
  269. https://www.illumina.com/content/dam/illumina-marketing/documents/icommunity/article_2014_10_pedv_li.pdf
  270. https://ourworldindata.org/grapher/ghg-per-kg-poore
  271. https://www.bbc.com/future/article/20221214-what-is-the-lowest-carbon-protein
  272. https://www.ccacoalition.org/resources/review-greenhouse-gas-emissions-pig-houses-production-carbon-dioxide-methane-and-nitrous
  273. https://awellfedworld.org/feed-ratios/
  274. https://www.forestsoftheworld.org/forest-clearing/soy/
  275. https://pmc.ncbi.nlm.nih.gov/articles/PMC4750877/
  276. https://porkgateway.org/resource/energy-and-nutrient-recovery-from-swine-manures/
  277. https://sera17.wordpress.ncsu.edu/treating-liquid-swine-and-dairy-manure-with-aluminum-chloride/
  278. https://porkcheckoff.org/wp-content/uploads/2021/02/Comprehensive-Report-LU-LCA-13-208-updated-6.8.2020.pdf
  279. https://porcinehealthmanagement.biomedcentral.com/articles/10.1186/s40813-023-00347-5
  280. https://pmc.ncbi.nlm.nih.gov/articles/PMC5666184/
  281. https://porcinehealthmanagement.biomedcentral.com/articles/10.1186/s40813-016-0020-7
  282. https://www.tandfonline.com/doi/full/10.4081/ijas.2014.3095
  283. https://pmc.ncbi.nlm.nih.gov/articles/PMC6325398/
  284. https://pmc.ncbi.nlm.nih.gov/articles/PMC5710152/
  285. https://agreenerworld.org/certifications/animal-welfare-approved/standards/pig-standards/
  286. https://globalanimalpartnership.org/wp-content/uploads/2022/07/G.A.P.-Animal-Welfare-Standards-for-Pigs-v2.5.20220726.pdf
  287. https://awionline.org/sites/default/files/uploads/documents/AWI-Comments-PorkCARE-Standards.pdf
  288. https://orgprints.org/18711/1/Edwards-Pigs-ethical-concerns.pdf
  289. https://www.researchgate.net/publication/233574843_Anthropomorphism_and_anthropocentrism_as_influences_in_the_quality_of_life_of_companion_animals
  290. https://pmc.ncbi.nlm.nih.gov/articles/PMC9854468/
  291. https://www.sciencedirect.com/science/article/pii/S1751731114001359
  292. https://www.scirp.org/journal/paperinformation?paperid=85479
  293. https://asktheology.com/christians-eat-pork/
  294. https://christianity.stackexchange.com/questions/79917/why-do-most-christians-eat-pork-when-deuteronomy-says-not-to
  295. https://www.epoojastore.com/devotional-articles/pig-hinduism
  296. https://www.downtoearth.org.in/governance/the-pigs-dual-status-in-hinduismas-both-divine-and-pollutedreveals-the-contingent-nature-of-sacredness
  297. https://www.chinahighlights.com/travelguide/chinese-zodiac/pig.htm
  298. https://www.buffalo.edu/news/releases/2000/08/4837.html
  299. https://ukrainianvintage.com/en-ca/blogs/artisticwonders-unveiling-the-mysteries-of-masterpieces/the-art-of-pig-from-symbols-to-history-in-painting
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