Pigs are amenable to many different styles of farming: intensive commercial units, commercial free range enterprises, or extensive farming (being allowed to wander around a village, town or city, or tethered in a simple shelter or kept in a pen outside the owner's house). Historically, farm pigs were kept in small numbers and were closely associated with the residence of the owner, or in the same village or town.[1] They were valued as a source of meat and fat, and for their ability to convert inedible food into meat and manure, and were often fed household food waste when kept on a homestead.[2] Pigs have been farmed to dispose of municipal garbage on a large scale.[3]
All these forms of pig farm are in use today, though intensive farms are by far the most popular, due to their potential to raise a large amount of pigs in a very cost-efficient manner.[4] In developed nations, commercial farms house thousands of pigs in climate-controlled buildings.[5] Pigs are a popular form of livestock, with more than one billion pigs butchered each year worldwide, 100 million in the United States. The majority of pigs are used for human food, but also supply skin, fat and other materials for use in clothing, ingredients for processed foods,[6] cosmetics,[7] and medical use.[8]
Pigs are farmed in many countries, though the countries mainly consuming them are in Asia, meaning there is a significant international and even intercontinental trade in live and slaughtered pigs. Despite having the world's largest herd, China is a net importer of pigs as China consumes about 50% of global pork production.[9] The total amount of pork consumed in China is 57 million tons (as of 2021) and pork accounted for 60 percent of total meat consumption within the country.[10] China has been increasing its imports during its economic development; many within China's population of 1.2 billion people prioritize eating pork as their main consumption of meat, unlike other countries where most people would prioritize having poultry.[10] In addition, since 2007, China possesses a strategic pork reserve with a government mandate to "stabilize live hog prices, prevent excessive hog price drops, which damage the interests of farmers and to ease the negative effects of the cyclical nature of hog production and market prices." In China, the government actively intervened in the pork market during periods of instability by releasing pork reserves into the market whenever hogs get too expensive in China, in order to hold down prices for consumers. Conversely when prices of pork are deemed too low and unsustainable for farmers, the reserve buys up pigs to ensure farmers remain profitable.[11]
The largest exporters of pigs are the United States, the European Union, and Canada. As an example, more than half of Canadian production (22.8 million pigs) in 2008 was exported, going to 143 countries.[12]
Among animals raised for their meat, pigs have a lower feed conversion ratio than cattle, which can provide an advantage in lower unit price of meat because the cost of animal feed per kilogram or pound of resultant meat is lower. However, there are also many other economic variables in meat production and distribution, so the price differential of pork and beef at the point of retail sale does not always correspond closely to the differential in feed conversion ratios. Nonetheless, the favorable ratio often tends to make pork more affordable compared to beef.[13][14]
Relationship between handlers and pigs
The way in which a stockperson interacts with pigs affects animal welfare which in some circumstances can correlate with production measures. Many routine interactions can cause fear, which can result in stress and decreased production.
There are various methods of handling pigs which can be separated into those which lead to positive or negative reactions by the animals. These reactions are based on how the pigs interpret a handler's behavior.
Negative interactions
Many negative interactions with pigs arise from stock-people dealing with large numbers of pigs. Because of this, many handlers can become complacent about animal welfare and fail to ensure positive interactions with pigs. Negative interactions include overly heavy tactile interactions (slaps, punches, kicks, and bites), the use of electric goads and fast movements. It can also include killing them. However, it is not a commonly held view that death is a negative interaction. These interactions can result in fear in the animals, which can develop into stress. Overly heavy tactile interactions from the human handlers can cause increased basal cortisol levels (a "stress" hormone).[15] Negative interactions that cause fear mean the escape reactions of the pigs can be extremely vigorous, thereby risking injury to both stock and handlers. Stress can result in immunosuppression,[16] leading to an increased susceptibility to disease. Studies have shown that these negative handling techniques result in an overall reduction in growth rates of pigs.
"In Canada the Federal government does not regulate the treatment on farms and most provinces have animal cruelty legislation but they typically contain expectations for general agricultural practices." Due to this lack of legislation, this perpetuates to the cruel treatment of swine.[17] "The NFACC codes of practice are developed larger by the industry and are not enforced with third party oversight."[17]
Positive interactions
Various interactions can be considered either positive or neutral. Neutral interactions are considered positive because, in conjunction with positive interactions, they contribute to an overall non-negative relationship between the pig handler and the animal livestock. Pigs are often fearful of fast movements. When entering a pen, it is good practice for the pig handler to enter with slow and deliberate movements. These minimize fear and therefore reduce stress. Pigs are very curious animals. Allowing the pigs to approach and smell whilst patting or resting a hand on the pig's back are examples of positive behavior. Pigs also respond positively to verbal interaction. Minimizing fear of humans allow handlers to perform husbandry practices in a safer and more efficient manner. By reducing stress, stock are made more comfortable to feed when near the pig handlers, resulting in increased productivity.[18]
Impacts on sow breeding
Hogs raised in confinement systems tend to produce 23.5 piglets per year. Between 2013 and 2016, sow death rates nearly doubled in the United States, from 5.8 to 10.2 percent. 25 to 50 percent of deaths were caused by prolapse.[19]
Other probable causes of death include vitamin deficiency, mycotoxins in feed, high density diets or abdominal issues.[20]Iowa's Pork Industry Center collects mortality data in collaboration with the National Pork Board to collect data from over 400,000 sows from 16 U.S. states. The farms range in size and facility types. Increasing death rates are a profit concern to the industry, so money is invested into research to find solutions.[21]
Genetic manipulation
Pigs were originally bred to rapidly gain weight and backfat in the late 1980s. In a more fat-conscious modern day America, pigs are now being bred to have less back fat and produce more offspring, which pushes the sow's body too far and is deemed one of the causes of the current prolapse epidemic. Researchers and veterinarians are seeking ways to positively impact the health of the hogs and benefit the hog business without taking much from the economy.[22]
Stag, male pig castrated later in life (castrated after maturity)
Gilt, young female not yet mated, or not yet farrowed, or after only one litter (depending on local usage).[24]
Sow, breeding female, or female after first or second litter
Pigs for slaughter
Finishing pigs on a farm
Suckling pig, a piglet slaughtered for its tender meat
Feeder pig, a weaned gilt or barrow weighing between 18kg (40lb) and 37kg (82lb) at 6 to 8 weeks of age that is sold to be finished for slaughter
Porker, market pig between 30kg (66lb) and about 54kg (119lb) dressed weight
Baconer, a market pig between 65kg (143lb) and 80kg (180lb) dressed weight. The maximum weight can vary between processors.
Grower, a pig between weaning and sale or transfer to the breeding herd, sold for slaughter or killed for rations.[clarification needed]
Finisher, a grower pig over 70kg (150lb) liveweight
Butcher hog, a pig of approximately 100kg (220lb), ready for the market. In some markets (Italy) the final weight of butcher pig is in the 180kg (400lb) range. They tend to have hind legs suitable to produce cured ham
Backfatter, cull breeding pig sold for meat; usually refers specifically to a cull sow, but is sometimes used in reference to boars
Groups
Herd, a group of pigs, or all the pigs on a farm or in a region
Sounder, a small group of pigs (or wild boar) foraging in woodland
Pig parts
Trotters, the hooves of pigs (they have four hoofed toes on each foot, walking mainly on the larger central two)
Feces and waste often spread to surrounding neighborhoods, polluting air and water with toxic waste particles.[25] Waste from swine on these farms carry a host of pathogens and bacteria as well as heavy metals. These toxins can leach down through the soil into groundwater, polluting local drinking water supplies. Pathogens can also become airborne, polluting the air and harming individuals when ingested.[26] Contents from waste have been shown to cause detrimental health implications, as well as harmful algal blooms in surrounding bodies of water.[27] Due to Concentrated Animal Feed Operations (CAFOs), those who live in the surrounding areas of pig farms tend to experience health complications. Symptoms included headaches, nausea, and weakness due to the fumes that are emitted from these farms.[citation needed] Those who work directly inside these farms often experience these symptoms more intensely. Typically, workers of these farms experience respiratory issues such as wheezing, coughing, and tightness of the chest as well as eye and nasal irritation.[28] This is in part due to the air quality being poor because of the air particles being contaminated with hog feces.[citation needed]
Little to no regulation has been written by the EPA and federal legislators surrounding CAFOs to protect the welfare of both the environment and humans from their impacts.[29] The only permit required by federal law on wastewater runoff by CAFOs is the National Pollutant Discharge Elimination System (NPDES) permit. NPDES are authorized under the Clean Water Act and aim to reduce dumping of pollutants in water systems.[30] However, one of the most detrimental waste management practices used at swine farms, manure lagoons, have little to no regulations surrounding waste management, as they are not connected to a moving water source and therefore is not seen as an imminent threat to human or environmental health.[31]
Occupational hazards
Common occupational hazards faced by pig farmers include but are not limited to exposure to toxic gases and particulate matter.[32][33][34] The Occupational Safety and Health Administration or OSHA sets health and safety standards for hazardous substances in the workplace called permissible exposure limits or PELs.[35] Specific PELs exist for toxic gases and particulate matter and these standards are legally enforced by OSHA to ensure that the safety and health of workers are protected.[35]
Toxic Gas and Particulate Matter Exposure
Toxic gases can accumulate to dangerous levels in pig barns
Toxic gases including hydrogen sulfide, ammonia, methane and carbon dioxide are produced as a result of the decomposition of pig feces and these gases become highly concentrated in enclosed spaces of pig barns which can be hazardous to health when inhaled.[36]Carbon monoxide is another commonly associated toxic gas that can accumulate in pig barns as a result of the trapping of combustion byproducts such as malfunctioning furnaces or gas heat sources in the absence of adequate ventilation.[37]
Hydrogen sulfide gas has a foul, "rotten eggs" smell at low concentrations but paralyzes the olfactory nerve at higher concentrations so that no smell is sensed.[38] Exposure to high levels, well beyond the OSHA PEL, of hydrogen sulfide can cause fatal respiratory paralysis.[36] The common source of hydrogen sulfide are covered manure pits below the pig barns that act as feces reservoirs.[38] These manure pits require regular emptying and during this process, high levels of hydrogen sulfide is released and seeps into pig barns.[36] Pig barns must be void of any human or animal inhabitants during this emptying process and require a several hour "waiting period" until occupants can safely reenter the barn.[36]
Ammonia gas has a strong odor that can be smelled at low levels, below the OSA PEL, but does not have any negative health effects.[39] At higher levels, ammonia is irritating to the body's mucous membranes such as the eyes, nose, mouth, throat and lungs.[39] Particulate matter in pig barns often absorbs ammonia as it floats through the air.[40] These particles are then inhaled and increase the irritating effect of ammonia.[40]
Methane and carbon dioxide are combustible gases meaning that they can burn, catch fire or explode easily.[41] They are also known as chemical asphyxiants and at high levels can cause suffocation by displacing oxygen from the air.[41]
Particulate matter is produced when small fragments of pig hair or skin, dried feces, or feed can detach and become suspended in the air in pig barns.[40] The increased concentration of particulate matter in the air, especially in confined spaces, can lead to respiratory tract irritation and other health effects when inhaled.[40] Bacteria and viruses, such as influenza, can travel through the air on particulate matter and increase the risk of transmission of disease.[40]
OSHA requires that toxic gas and particulate matter be measured at least twice yearly preferably in the autumn months and again in the winter when natural ventilation is the most reduced.[42] Workers are also advised to wear N-95 respirators and eye protection when inside of pig barns to prevent the inhalation of toxic gases and particulate matter as well as irritation to the of eyes.[38][42]
Geopolitical issues
As with other commodities, pork presents challenges in the politics of international trade as national interests compete and seek economic modus vivendi. Changes to policy can upset the existing balances, prompting economic anxiety. For example, in 2020, the hog farming sector in Taiwan was upset by a decision to allow imports from the United States without labeling of ractopamine use.[43] Farmers' views varied on how negative the effects might be.[43] Issues of pride and degree of autarky also figure into such debates; people understandably wonder whether trade competition changes will deeply damage domestic production capability, while accurate quantitative answers are often difficult to find amid the mass of debate.[43]
Drugs
Growth promoters
Ractopamine
Most pigs in the US receive ractopamine which promotes muscle instead of fat, quicker weight gain, and reduced costs and pollutants in the environment. Such pigs consume less feed to reach finishing weight and produce less manure. Ractopamine has not been approved for use by the European Union, China, Russia, and several other countries.[44]
Colistin
China once used colistin (an antibiotic) as growth promoter (subtherapeutic antibiotic use) but discovered a colistin-resistant form of E. coli bacteria in a pig from a Shanghai farm in 2013. Investigations then led to the identification of "a gene called MCR-1 that allowed bacteria to survive colistin treatment in animals and humans."[45] In 2016, these findings led China to ban colistin as growth promoter.[45][46]
Antibiotics
A systematic review found that penicillins and tetracyclines were the most commonly used antibiotics in pigs.[47]
Parasites
Toxoplasmosis is a constant pressure on pig farming. Worldwide, the percentage of pigs harboring viable Toxoplasma gondii parasites has been measured to be 3% to 71.43%.[48] Surveys of seroprevalence (T. gondii antibodies in blood) are more common, and such measurements are indicative of the high relative seroprevalence in pigs across the world.[49]:145–151 Neonatal piglets have been found to suffer the entire range of severity, including progression to stillbirth.[49]:153[50]:95 This was especially demonstrated in the foundational Thiptara et al. 2006, reporting a litter birth of three stillborns and six live in Thailand. This observation has been relevant not only to that country but to toxoplasmosis control in porciculture around the world.[51][50]:95[48]
Hygiene
Excessively hygienic raising conditions were found to prevent proper gut microbiota development by Schmidt et al. 2011.[52] Moore et al. 1995 describes the pathology of Cryptosporidium infection, a common difficulty in piglet production.[53]
In an attempt to curb diseases such as African swine fever,[54] a number of Chinese companies have built condominium-style mega complexes multiple stories high to house thousands of pigs. The buildings have been dubbed "hog hotels" and come with strict protocols and advanced cleaning, veterinary, and disposal systems.[54][55] However, doubt has been raised by policy specialists and animal scientists over the facilities' efficacy in preventing outbreaks. The welfare of the animals has also been a source of concern, and it has been suggested that the poor welfare of the pigs may cause a decline in their immunity.[56]
Sus is the genus of domestic and wild pigs, within the even-toed ungulate family Suidae. Sus include domestic pigs and their ancestor, the common Eurasian wild boar, along with various other species. Sus species, like all suids, are native to the Eurasian and African continents, ranging from Europe to the Pacific islands.
Intensive pig farming, also known as pig factory farming, is the primary method of pig production, in which grower pigs are housed indoors in group-housing or straw-lined sheds, whilst pregnant sows are housed in gestation crates or pens and give birth in farrowing crates.
An anaerobic lagoon or manure lagoon is a man-made outdoor earthen basin filled with animal waste that undergoes anaerobic respiration as part of a system designed to manage and treat refuse created by concentrated animal feeding operations (CAFOs). Anaerobic lagoons are created from a manure slurry, which is washed out from underneath the animal pens and then piped into the lagoon. Sometimes the slurry is placed in an intermediate holding tank under or next to the barns before it is deposited in a lagoon. Once in the lagoon, the manure settles into two layers: a solid or sludge layer and a liquid layer. The manure then undergoes the process of anaerobic respiration, whereby the volatile organic compounds are converted into carbon dioxide and methane. Anaerobic lagoons are usually used to pretreat high strength industrial wastewaters and municipal wastewaters. This allows for preliminary sedimentation of suspended solids as a pretreatment process.
The pig, also called swine, piggy, oinker, 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. It is considered a subspecies of Sus scrofa by some authorities, but as a distinct species by others. Pigs were domesticated in the Neolithic, both in East Asia and in the Near East. When domesticated pigs arrived in Europe, they extensively interbred with wild boar but retained their domesticated features.
The Gloucestershire Old Spots is an English breed of pig which is predominantly white with black spots. It is named after the county of Gloucestershire. The Gloucestershire Old Spots pig is known for its docility, intelligence, prolificity, and hardiness. Boars reach a mature weight of 600 lb (272 kg) and sows 500 lb (227 kg). The pigs are white with clearly defined black spots. There must be at least one spot on the body to be accepted in the registry. The breed's maternal skills enable it to raise large litters of piglets on pasture. Its disposition and self‑sufficiency should make it attractive for farmers raising pasture pigs and those who want to add pigs to diversified operations.
Smithfield Hog Production Division, formerly Premium Standard Farms, Inc. (PSF), is a subsidiary of Smithfield Foods, Inc.
African swine fever virus (ASFV) is a large, double-stranded DNA virus in the Asfarviridae family. It is the causative agent of African swine fever (ASF). The virus causes a hemorrhagic fever with high mortality rates in domestic pigs; some isolates can cause death of animals as quickly as a week after infection. It persistently infects its natural hosts, warthogs, bushpigs, and soft ticks of the genus Ornithodoros, which likely act as a vector, with no disease signs. It does not cause disease in humans. ASFV is endemic to sub-Saharan Africa and exists in the wild through a cycle of infection between ticks and wild pigs, bushpigs, and warthogs. The disease was first described after European settlers brought pigs into areas endemic with ASFV, and as such, is an example of an emerging infectious disease.
Smithfield Foods, Inc., is an American pork producer and food-processing company based in Smithfield, Virginia. It operates as an independent subsidiary of the Chinese multinational conglomerate WH Group. Founded in 1936 as the Smithfield Packing Company by Joseph W. Luter and his son, the company is the largest pig and pork producer in the world. In addition to owning over 500 farms in the US, Smithfield contracts with another 2,000 independent farms around the country to raise Smithfield's pigs. Outside the US, the company has facilities in Mexico, Poland, Romania, Germany, Slovakia and the United Kingdom. Globally the company employed 50,200 in 2016 and reported an annual revenue of $14 billion. Its 973,000-square-foot meat-processing plant in Tar Heel, North Carolina, was said in 2000 to be the world's largest, slaughtering 32,000 pigs a day.
A gestation crate, also known as a sow stall, is a metal enclosure in which a farmed sow used for breeding may be kept during pregnancy. A standard crate measures 6.6 ft x 2.0 ft.
Intensive animal farming, industrial livestock production, and macro-farms, also known as factory farming, is a type of intensive agriculture, specifically an approach to animal husbandry designed to maximize production while minimizing costs. To achieve this, agribusinesses keep livestock such as cattle, poultry, and fish at high stocking densities, at large scale, and using modern machinery, biotechnology, and global trade. The main products of this industry are meat, milk and eggs for human consumption.
Ractopamine is an animal feed additive used to promote leanness and increase food conversion efficiency in farmed animals in several countries, but banned in others. Pharmacologically, it is a phenol-based TAAR1 agonist and β adrenoreceptor agonist that stimulates β1 and β2 adrenergic receptors. It is most commonly administered to animals for meat production as ractopamine hydrochloride. It is the active ingredient in products marketed in the US as Paylean for swine, Optaflexx for cattle, and Topmax for turkeys. It was developed by Elanco Animal Health, a former division of Eli Lilly and Company.
The Large Black is a British breed of domestic pig. It is the only British pig that is entirely black. It was created in the last years of the nineteenth century by merging the black pig populations of Devon and Cornwall in the south-west with those of Essex, Suffolk and Kent in the south-east. It is hardy, docile and prolific; it forages well and is suitable for extensive farming, but not well suited to intensive management.
Deep litter is an animal housing system, based on the repeated spreading of straw or sawdust material in indoor booths. An initial layer of litter is spread for the animals to use for bedding material and to defecate in, and as the litter is soiled, new layers of litter are continuously added by the farmer. In this fashion, a deep litter bedding can build up to depths of 1–2 meters. "The usual procedure for built-up floor litter is to start with about 4 inches (100 mm) of fine litter material with additions of 1 to 2 inches later as needed without removal of the old. A depth of 6 to 12 inches is maintained by partial removals from time to time." Many consider this to be a natural means to disposing of animal feces. "The deep litter cultivation is a modern ecological breeding technique based on decomposing feces by microbiological methods, a post processing method for poultry Manure."
Manure management refers to capture, storage, treatment, and utilization of animal manures in an environmentally sustainable manner. It can be retained in various holding facilities. Animal manure can occur in a liquid, slurry, or solid form. It is utilized by distribution on fields in amounts that enrich soils without causing water pollution or unacceptably high levels of nutrient enrichment. Manure management is a component of nutrient management.
The Swabian-Hall swine is a breed of domestic pig originating from Schwäbisch Hall in Baden-Württemberg, Germany. It is a large pig, white in the centre with a black head and rear and narrow grey bands at the transition from white to black skin. They have large litters averaging more than nine piglets.
Risk assessment for organic swine health is the process of evaluating the likelihood and potential impact of various factors that may affect the health and well-being of organic swine. Risks associated with organic swine farming may differ to those associated with non-organic swine farming, and is of increasing relevance due to growth in the sector. While organic swine farming makes up a small share of U.S. swine farming overall, numbers have increased significantly in recent years. Additionally, non-certified organic swine herds are not accounted in official statistics. Consumer demand, stemming from the larger organic agriculture movement has helped spur growth in this industry.
Farmageddon: The True Cost of Cheap Meat is a 2014 non-fiction book by Philip Lymbery and Isabel Oakeshott. It surveys the effects of industrial livestock production and industrial fish farming around the world. The book is the result of Lymbery's investigations for which he travelled the world over three years. Isabel Oakeshott is the political editor of The Sunday Times, Lymbery is CEO of Compassion in World Farming. The book was published by Bloomsbury.
The environmental impact of pig farming is mainly driven by the spread of feces and waste to surrounding neighborhoods, polluting air and water with toxic waste particles. Waste from pig farms can carry pathogens, bacteria, and heavy metals that can be toxic when ingested. Pig waste also contributes to groundwater pollution in the forms of groundwater seepage and waste spray into neighboring areas with sprinklers. The contents in the spray and waste drift have been shown to cause mucosal irritation, respiratory ailment, increased stress, decreased quality of life, and higher blood pressure. This form of waste disposal is an attempt for factory farms to be cost efficient. The environmental degradation resulting from pig farming presents an environmental injustice problem, since the communities do not receive any benefit from the operations, and instead, suffer negative externalities, such as pollution and health problems. The United States Agriculture and Consumer Health Department has stated that the "main direct environmental impact of pig production is related to the manure produced.
Muyuan Foodstuff is a Chinese food company specializing in pork production. As of 2023, Muyuan raises approximately 60 million and slaughters 13 million pigs per year. They operate the world's largest pig farm.
Wens Foodstuff Group is a Chinese food company specializing in pork production.
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