|A pig oinking|
The pig (Sus domesticus), often called swine, hog, or domestic pig when distinguishing from other members of the genus
When used as
The pig typically has a large head, with a long snout which is strengthened by a special prenasal bone and a disk of
Four hoofed toes are on each foot, with the two larger central toes bearing most of the weight, but the outer two also being used in soft ground.
Most pigs have rather a
Pigs possess both
Pigs are one of four known mammalian species which possess mutations in the nicotinic acetylcholine receptor that protect against snake venom. Mongooses, honey badgers, hedgehogs, and pigs all have modifications to the receptor pocket which prevents the snake venom α-neurotoxin from binding. These represent four separate, independent mutations.
Pigs have small lungs in relation to their body size, and are thus more susceptible than other domesticated animals to fatal bronchitis and pneumonia. Pigs have a maximum life span of about 27 years.
Genetics and genomics
The genome of the pig has been sequenced and contains about 22,342 protein-coding genes.
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. 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, which is still used by some taxonomists. The American Society of Mammalogists considers it a separate species.
Archaeological evidence suggests that pigs were
In the Near East, pig husbandry spread for the next few millennia. It reduced gradually during the Bronze Age, as rural populations focused instead on commodity-producing livestock. It was sustained in urbanized regions, however.
DNA evidence from subfossil remains of teeth and jawbones of Neolithic pigs shows that the first domestic pigs in Europe had been 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. Modern domesticated pigs have involved complex exchanges, with European domesticated lines being exported, in turn, to the ancient Near East. Historical records indicate that Asian pigs were introduced into Europe during the 18th and early 19th centuries.
In August 2015, a study looked at over 100 pig genome sequences to ascertain their process of domestication, which was assumed to have been initiated by humans, involved few individuals, and relied on reproductive isolation between wild and domestic forms. The study found that the assumption of reproductive isolation with population bottlenecks was not supported. The study indicated that pigs were domesticated separately in Western Asia and China, with Western Asian pigs introduced into Europe, where they crossed with wild boar. A model that fit the data included a mixture with a now extinct ghost population of wild pigs during the Pleistocene. The study also found that despite back-crossing with wild pigs, the genomes of domestic pigs have strong signatures of selection at DNA loci that affect behavior and morphology. The study concluded that human selection for domestic traits likely counteracted the homogenizing effect of gene flow from wild boars and created domestication islands in the genome. The same process may also apply to other domesticated animals. In 2019, a study showed that the pig had arrived in Europe from the Near East 8,500 years ago. Over the next 3,000 years they then admixed with the European wild boar until their genome showed less than 5% Near Eastern ancestry, yet retained their domesticated features.
Among the animals that the Spanish
With around 1 billion individuals alive at any time, the domesticated pig is one of the most numerous large mammals on the planet.
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.
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 will trigger the female's response. The female cervix contains a series of five interdigitating pads, or folds, that will hold the boar's corkscrew-shaped penis during copulation. Females have bicornuate uteruses and two conceptuses must be present in both uterine horns for pregnancy to be established. Maternal recognition of pregnancy in pigs occurs on days 11 to 12 of pregnancy and is marked by progesterone production from a functioning corpus luteum (CL). To avoid luteolysis by PGF2α, rescuing of the CL must occur via embryonic signaling of estradiol 17β and PGE2. This signaling acts on both the endometrium and luteal tissue to prevent the regression of the CL by activation of genes that are responsible for CL maintenance. During mid to late pregnancy, the CL relies primarily on luteinizing hormone (LH) for maintenance until parturition. Animal nutrition is important prior to reproduction and during gestation to ensure optimum reproductive performance is achieved.
Archeological evidence indicates that medieval European pigs farrowed, or bore a litter of piglets, once per year. By the nineteenth century, European piglets routinely double-farrowed, or bore two litters of piglets per year. It is unclear when this shift occurred.
In many ways pig behaviour appears to be intermediate between that of other
Because of their relative lack of sweat glands, pigs often control their body temperature using behavioural thermoregulation. Wallowing, which often consists of coating the body with mud, is a behaviour frequently exhibited by pigs. They do not submerge completely under the mud, but vary the depth and duration of wallowing depending on environmental conditions. Typically, adult pigs start wallowing once the ambient temperature is around 17–21 °C (63–70 °F). They cover themselves from head to toe in mud. Pigs may use mud as a sunscreen, or as a method of keeping parasites away. Most bristled pigs will "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.
If conditions permit, pigs feed continuously for many hours and then sleep for many hours, in contrast to
Rooting is an instinctual behavior in pigs that is characterized by a pig nudging its snout into something. Similar to a cat's kneading, rooting is found comforting. It first happens when piglets are born to obtain their mother's milk, and can become a habitual, obsessive behavior which is most prominent in animals weaned too early. Often, pigs will root and dig into the ground to forage for food. By means of rooting, pigs have been used to till farmland.
Rooting is known to also be used as a means of communication.
The breed known as the kunekune hardly ever roots, as it can sustain itself by feeding on nothing other than grass. Not having to root around in the soil to find underground food (e.g. tubers), it thus has evolved to, for the most part, not possess the instinct for rooting.
A behavioural characteristic of pigs which they share with carnivores is
Nest-building behaviour is an important part in the process of pre and post-partum maternal behaviour. Nest-building will occur during the last 24 hours before the onset of farrowing and becomes most intense during 12 to 6 hours before farrowing. Nest-building is divided into two phases: one of which is the initial phase of rooting in the ground while the second phase is the collecting, carrying and arranging of the nest material. The sow will separate from the group and seek a suitable nest site with some shelter from rain and wind that has well-drained soil. This nest-building behaviour is performed to provide the offspring with shelter, comfort, and thermoregulation. The nest will provide 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 that other piglets are not stealing milk from the sow. Nest-building can be influenced by internal and external stimuli. Internal hormonal changes and the completion of one nesting phase are indicators of this maternal behaviour. The onset is triggered by the rise in prolactin levels, which is caused by a decrease in progesterone and an increase in prostaglandin, while the gathering of the nest material seems to be regulated more by external stimuli such as temperature. The longer time spent on nest-building will increase pre-partum oxytocin.
Nursing and suckling behaviour
Pigs display complex nursing and suckling behaviour. 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. 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.
The phase of competition for teats and of nosing the udder lasts for about one minute and ends when milk flow begins. In the third phase, the piglets 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. 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 then 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 greater the future milk release from that teat will be.
Pigs have a well-developed sense of smell, and use is made of this in Europe where they are trained to locate underground
When in use as livestock, the pig is mostly farmed for its meat, pork. Other food products made from pigs include pork
The use of pig milk for human consumption does take place, but as there are certain difficulties in obtaining it, there is little commercial production.
Livestock pigs are exhibited at agricultural shows, judged either as stud stock compared to the standard features of each pig breed, or in commercial classes where the animals are judged primarily on their suitability for slaughter to provide premium meat.
Vietnamese pot-bellied pigs, a miniature breed of pig, have made popular pets in the United States, beginning in the latter half of the 20th century.
In many respects, pot-bellied pigs are desirable and entertaining pets. They are considered intelligent, gregarious, and trainable. They lack the genetic hereditary weaknesses which commonly afflict certain pedigree cat and dog breeds, are generally quite sturdy, and have a reasonably affordable diet despite requiring large quantities of food. However, they can be strong-willed, defiant, and independent pets which will sometimes defy training. They require access to an outdoor space at all times, and depending on the individual pig, may become housebroken easily or never settle indoors. While hardy, an injured or sick pig will require costly surgery or larger than average quantities of medicine than most pets.
Pigs are highly intelligent, social creatures. They are considered hypoallergenic, and are known to do quite well with people who have the usual animal allergies. Since these animals are known to have a life expectancy of 15 to 20 years, they require a long-term commitment.
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 to dogs and exhibit fight-or-flight instincts, independent nature, and natural assertiveness which can manifest as aggression towards children and a tendency to panic and lash out with little warning. Cats generally are safe around pigs as neither species has an incentive to express aggression or fear towards the other, although dogs will view pigs as prey animals and in turn, pigs will challenge dogs for food, leading to very violent fights.
Male and female swine that have not been de-sexed may express unwanted aggressive behavior, and are prone to developing serious health issues. Regular trimming of the hooves is necessary; hooves left untreated cause major pain in the pig, can create malformations in bone structure and may cause the pig to be more susceptible to fungal growth between crevices of the hoof, or between the cracks in a split hoof. Male pigs, especially when left unaltered, can grow large, sharp tusks which may continue growing for years. Domestic owners may wish to keep their pigs' tusks trimmed back, or have them removed entirely.
As prey animals, pigs' natural instinctive behavior causes them to have a strong fear of being picked up, resulting in the animal expressing stress through struggling and squealing, but they will usually calm down once placed back onto the ground. This instinctual fear may be lessened if the pig has been frequently held since infancy. When holding pigs, supporting them under the legs makes being held not as stressful for the animal. Pigs need enrichment activities to keep their intelligent minds occupied; if pigs get bored, they often become destructive. As rooting is found to be comforting, pigs kept in the house may root household objects, furniture or surfaces. While some owners are known to pierce their pigs' noses to discourage rooting behaviour, the efficacy and humaneness of this practice is questionable. Pet pigs should be let outside daily to allow them to fulfill their natural desire of rooting around.
In human medical applications
Pigs, both as live animals and a source of post-mortem tissues, are one of the most valuable animal models used in biomedical research today, 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. Porcine[clarification needed] are used in finding treatments, cures for diseases, xenotransplantation, and for general education. They are also used in the development of medical instruments and devices, surgical techniques and instrumentation, and FDA-approved research. These animals contribute to the reduction methods for animal research, as they supply more information from fewer animals used, for a lower cost.
Pigs are currently thought to be the best non-human candidates for organ donation to humans, and to date they are the only animal that has successfully donated an organ to a human body. The first successful donation of a non-human organ to a human body was conducted on 15 September 2021, when a kidney from a pig was transplanted to a brain-dead human and immediately started functioning similarly to a human kidney. The procedure, led by Dr. Robert Montgomery, used a donor pig that was genetically engineered to not have a specific carbohydrate that the human body considers a threat–Galactose-alpha-1,3-galactose. This followed an earlier major breakthrough when the carbohydrate was removed from genetically engineered mice.
Besides similarity between pig and human organs, pigs are among the best animals suited for human donation due the lower risk of cross-species disease transmission. This is caused by pigs' increased phylogenetic distance from humans. Furthermore, they are readily available, and new infectious agents are less likely since they have been in close contact with humans through domestication for many generations.
Some obstacles to successful organ donation from a pig to a human arise from the response of the recipient's
Examples of viruses carried by pigs include porcine
Pig cells have been engineered to inactivate all 62 PERVs in the genome using CRISPR Cas9 genome editing technology, and eliminated infection from the pig to human cells in culture.
In the belief of traditional Irish fishermen, the pig is seen as a thing of bad luck and should not be mentioned.
Glossary of terms
Because the pig is a major domesticated animal, English has many terms unique to the species:
- barrow – a castrated male swine
- boar – a mature male swine; often a wild or feral swine
- boneen – a very young pig (Ireland)
- farrow (noun) – a litter of piglets
- farrow (verb) – to give birth to piglets
- gilt – a female pig that has never been pregnant or is pregnant for the first time
- hog – a domestic swine, especially a fully-grown specimen
- parcel – collective noun for pigs
- pig – strictly, an immature swine; more generally, any swine, especially of the domestic variety
- piglet – a very young pig
- queen – a female pig that has never been mated
- savaging – the act of a sow attacking her own piglets, sometimes killing and cannibalising them
- shoat – a young pig, especially one that has been weaned
- sounder – collective noun for pigs
- sow – a mature female swine
- swine (singular and plural) – hogs collectively or generally; also a derogatory epithet
- swineherd – one who tends to swine raised as livestock; a pig farmer
- Mycoplasma hyorhinis
- Peccary (domestication)
- List of individual pigs
- List of pig breeds
- ^ David DiSalvo's article in Forbes refers to via an article in Penn State Agricultural Magazine referenced from 'Pork' by Catherine Becker at Ohio State University referencing work by Candace Croney, now head of Purdue center for animal welfare science.
- ^ a b "Sus scrofa (wild boar)". Animal Diversity Web.
- ^ Lockhart, Kim. "American Wild Game / Feral Pigs / Hogs / Pigs / Wild Boar". gunnersden.com. Archived from the original on 23 August 2018. Retrieved 15 August 2012.
- ^ "Royal visit delights at the Three Counties Show". Malvern Gazette.
- ^ Sumena, K.B.; Lucy, K.M.; Chungath, J.J.; Ashok, N.; Harshan, K.R. (2010). "Regional histology of the subcutaneous tissue and the sweat glands of large white Yorkshire pigs" (PDF). Tamilnadu Journal of Veterinary and Animal Sciences. 6 (3): 128–135.[permanent dead link]
- S2CID 28234765.
- ^ "Sweat like a pig?". Australian Broadcasting Corporation. 22 April 2008.
- PMID 25796346.
- ^ "Pros and Cons of Potbellied Pigs". Archived from the original on 17 March 2014. Retrieved 25 November 2017.
- PMID 32361879.
- PMID 27646534.
- PMID 32543654.
- PMID 35073880.
- ^ "Taxonomy Browser". ncbi.nlm.nih.gov.
- doi:10.1016/j.jas.2003.10.006. Archived from the original(PDF) on 8 April 2011.
- OCLC 62265494.
- ^ "Explore the Database". www.mammaldiversity.org. Retrieved 21 August 2021.
- ISBN 9781931707091.
- PMID 23180578.
our data suggest a narrative that begins with the domestication of pigs in Southwest Asia, at Upper Tigris sites including Çayönü Tepesi (Ervynck et al. 2001) and possibly Upper Euphrates sites including Cafer Höyük (Helmer 2008) and Nevalı Çori (Peters et al. 2005)
- S2CID 85302206.
- PMID 19706455.
- ^ PMID 10747069.
- ^ Jean-Denis Vigne; Anne Tresset; Jean-Pierre Digard (3 July 2012). History of domestication (PDF) (Speech).
- ^ Price, Max (March 2020). "The Genesis of the Near Eastern Pig". American Society of Overseas Research (ASOR). Retrieved 8 August 2021.
- ^ BBC News, "Pig DNA reveals farming history" 4 September 2007. The report concerns an article in the journal PNAS
- PMID 17855556.
- S2CID 205350534.
- PMID 31405970.
- ^ II.G.13. – Hogs. Archived 20 December 2007 at the Wayback Machine
- ^ "Feral Hogs in Missouri | Missouri Department of Conservation". mdc.mo.gov. Archived from the original on 8 March 2017. Retrieved 7 March 2017.
- ^ "Feral Hog Hunting Regulations". agfc.com. Archived from the original on 22 February 2017. Retrieved 7 March 2017.
- ^ "Feral Hog Management | Georgia DNR – Wildlife Resources Division". georgiawildlife.com. Archived from the original on 8 March 2017. Retrieved 8 March 2017.
- ^ Yoon, Carol Kaesuk (2 December 1992). "Alien Species Threaten Hawaii's Environment". The New York Times.
- ^ "Introduced Birds and Mammals in New Zealand and Their Effect on the Environment – NZETC". nzetc.org.
- ^ "World's 100 most destructive species named". The Independent. 21 November 2004. Archived from the original on 26 May 2022. Retrieved 7 March 2017.
- ^ Marília, Do G1 Bauru e (12 April 2013). "Autorização para abate do javaporco tranquiliza produtores em Assis, SP". Bauru e Marília.
- ^ "IBAMA authorizes capture and slaughter of 'javaporcos' – Folha do Sul Gaúcho". Archived from the original on 3 July 2017.
- ^ "Javaporco dá prejuízo e amedronta produtores rurais de Maracaí, SP".
- ^ MS Rural – farmers are authorized to make populational control of exotic species, such as the European boar Archived 12 October 2014 at the Wayback Machine (in Portuguese)
- ^ "Status and Distribution of wild boar in Rio Grande do Sul, Southern Brazil". 2009.
- ^ "PSD Online". fas.usda.gov.
- ^ Swine Summary Selected Countries Archived 29 March 2012 at the Wayback Machine, United States Department of Agriculture, Foreign Agricultural Service, (total number is Production (Pig Crop) plus Total Beginning Stocks
- ISBN 0408709464.
- ^ "Feral Hog Reproductive Biology". 16 May 2012.
- ^ "G2312 Artificial Insemination in Swine: Breeding the Female | University of Missouri Extension". extension.missouri.edu. Archived from the original on 8 March 2017. Retrieved 7 March 2017.
- ^ "The Female – Swine Reproduction". livestocktrail.illinois.edu. Retrieved 7 March 2017.
- PMID 3517318.
- PMID 22958877.
- ^ PMID 29794023.
- PMID 28628266.
- OCLC 899008362.
- ^ Ervynck, A., & Dobney, K. (2002). A Pig all Seasons? Approaches to the Assessment of Second Farrowing in Archaeological Pig Populations. Archaeofauna, (11).
- ISBN 978-0-470-99860-1.
- ^ a b c Clutton-Brock, J., (1987). A Natural History of Domesticated Mammals. Cambridge University Press, Cambridge pp.73–74
- S2CID 9742677.
- ^ "Blowing Coat – Mini Pig Shedding FAQ". americanminipigassociation.com. 2 April 2016.
- S2CID 84886946.
- ^ "10 of the smartest animals on Earth". MNN – Mother Nature Network. Retrieved 8 March 2017.
- ^ "Signs of Intelligent Life | Natural History Magazine". naturalhistorymag.com. Retrieved 3 June 2019.
- ^ David Disalvo 2014/11/26 how-smart-was-that-turkey-and-ham-before-it-became-dinner at forbes.com Accessed 27 January 2017
- ^ "In a Pig's Eye" – by Eston Martz Penn State Agricultural Magazine, Fall/ Winter 1997 Penn State College of Agricultural Sciences[permanent dead link] Accessed 27 January 2017
- ^ Catherine Becker: 'Pork' at u.osu.edu[permanent dead link] Accessed 27 January 2017
- ^ 'Croney to head Purdue Center for Animal Welfare Science' Accessed 27 January 2017
- ^ Angier, Natalie (9 November 2009). "Pigs Prove to Be Smart, if Not Vain". The New York Times. New York City. Retrieved 28 July 2010.
- ^ a b c "Rooting & Nudging Behaviors in Mini Pigs". americanminipigassociation.com. 8 June 2016.
- ^ "Kunekune pigs are just right for farm life". tractorsupply.com.
- ^ S2CID 9742677.
- S2CID 31788525.
- PMID 8226386.
- S2CID 12493158.
- PMID 4733757.
- ^ "Animalbehaviour.net (Pigs)". Archived from the original on 17 March 2012. Retrieved 9 December 2012.
- ^ "Animalbehaviour.net (Sheep)". Archived from the original on 26 December 2012. Retrieved 9 December 2012.
- ^ Houpt, K.A., (1998). Domestic Animal Behavior for Veterinarians and Animal Scientists. 3rd edition. Iowa State University Press, Ames.
- ^ Gonyou, H.W., (2001). The social behaviour of pigs. In "Social Behaviour in Farm Animals", eds. Keeling, L.J., and Gonyou, H.W. CABI, Oxford.
- S2CID 4386919.
- ^ "The Livestock Conservancy". livestockconservancy.org. Retrieved 7 March 2017.
- ^ "Taking good care of Ellegaard Göttingen Minipigs®" (PDF). Ellegaard Göttingen Minipigs. Archived from the original (PDF) on 19 April 2016. Retrieved 2 July 2018.
- ^ "FAOSTAT". fao.org. Retrieved 25 October 2019.
- ^ Strom, Stephanie (2 January 2014). "Demand Grows for Hogs That Are Raised Humanely Outdoors". The New York Times. Retrieved 15 April 2015.
- ^ "The Pros and Cons of Keeping Pot-Bellied Pigs as Pets". Did You Know Pets. 8 April 2020. Retrieved 10 November 2020.
- ^ "Info/Resource - Pigs 4 Ever - Gifts, supplies and resources for Pot-Bellied Pigs". pigs4ever.com. Retrieved 11 October 2020.
- ^ "Spay and Neuter – American Mini Pig Association". americanminipigassociation.com.
- ^ "Hoof Trimming – American Mini Pig Association". americanminipigassociation.com.
- ^ "Tusk Trimming in Mini Pigs Using Gigli Wire Saw -". 2 September 2016. Retrieved 7 May 2019.
- ^ "Mini Pig Training: How to Hold a Mini Pig – Life with a Mini Pig". 21 June 2015.
- ^ "Enrichment Activities for a Bored Pig – American mini Pig Association". Retrieved 7 May 2019.
- ^ "Aggressive Mini Pigs- How To Correct Aggression Issues". Mini Pig Info.
- ^ "Nose Rings in Mini Pigs, Cruel and Ineffective, Nose Ring Alternatives -". 1 September 2016. Retrieved 7 May 2019.
- ^ a b Herron, Alan J. (5 December 2009). "Pigs as Dermatologic Models of Human Skin Disease" (PDF). ivis.org. DVM Center for Comparative Medicine and Department of Pathology Baylor College of Medicine Houston, Texas. Retrieved 27 January 2018.
pig skin has been shown to be the most similar to human skin. Pigskin is structurally similar to the human epidermal and dermal-epidermal thickness ratios. Pigs and humans have similar hair follicle and blood vessel patterns in the skin. Biochemically, pigs contain dermal collagen and elastic content that is more similar to humans than other laboratory animals. Finally, pigs have similar physical and molecular responses to various growth factors.
- ^ a b Liu, J.; Kim, L.; Madsen, T.; Bouchard, G. F. "Comparison of Human, Porcine and Rodent Wound Healing With New Miniature Swine Study Data" (PDF). sinclairresearch.com. Sinclair Research Centre, Auxvasse, MO, USA; Veterinary Medical Diagnostic Laboratory, Columbia, MO, USA. Retrieved 27 January 2018.
Pig skin is anatomically, physiologically, biochemically and immunologically similar to human skin
- ^ "Xenotransplantation: How Pig Organs Could Be Transplanted into Humans". animalbiotech.com. Animal Biotech Industries. 19 March 2018. Retrieved 5 November 2018.
- ^ "Successful pig-to-human kidney transplant a "transformative moment"". www.yahoo.com. Retrieved 2 November 2021.
- ^ Lapid, Nancy (20 October 2021). "U.S. surgeons successfully test pig kidney transplant in human patient". Reuters. Retrieved 2 November 2021.
- ^ "Progress in Xenotransplantation Opens Door to New Supply of Critically Needed Organs". NYU Langone News. Retrieved 2 November 2021.
- S2CID 39194181.
- PMID 12612110.
- ^ Taylor, L. (2007) Xenotransplantation. Emedicine.com
- ^ FDA. (2006) Xenotransplantation Action Plan: FDA Approach to the Regulation of Xenotransplantation. Center for Biologics Evaluation and Research.
- ^ Carl Zimmerman (15 October 2015). "Editing of Pig DNA May Lead to More Organs for People". The New York Times.
- ISBN 978-0-9565628-7-6.
- ^ Dictionary of Agriculture (2006), "barrow," 21. "noun a male pig after castration, while a suckler or weaner"
- ^ Dictionary of Agriculture (2006), "boar," 30. "noun a male uncastrated pig"
- ^ Dictionary of Agriculture (2006), "farrowing," 97. "noun the act of giving birth to piglets"
- ^ Dictionary of Agriculture (2006), "gilt," 97. "noun a young female pig"
- ^ Dictionary of Agriculture (2006), "piglet," 189. "noun a young pig"
- ^ Dictionary of Agriculture (2006), "sow," 229. "noun a female pig"
- ^ Dictionary of Agriculture (2006), "swine," 240. "noun a collective term for pigs"
- Animal Welfare AVMA Policy on Pregnant Sow Housing
- Bateman, Heather; Curtis, Steve; McAdam, Katy, eds. (2006). Dictionary of Agriculture (3rd ed.). A & C Black. ISBN 978-0-7136-7778-2.
- CAST Scientific Assessment of the Welfare of Dry Sows kept in Individual Accommodations- March 2009
- Keuling, O.; Leus, K. (2019). "Sus scrofa". . Retrieved 11 November 2021.
- An introduction to pig keeping
- British Pig Association
- Globe and Mail article Canada's transgenic Enviropig is stuck in a genetic modification poke
- Information on Micro Pigs Archived 19 July 2019 at the Wayback Machine
- JJ Genetics, gilt pig breeders
- JSR Genetics, Pig genetics company
- Pig Sanctuary
- Swine Care
- Swine Study Guide from UC Davis
- The process of pig slaughtery