Is pig farming ecological in the 21st century

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  • Author David Steven Chalmers
  • Published October 17, 2023
  • Word count 3,107


In the 21st century it is becoming increasingly necessary to evaluate the environmental impact of various industries. One industry that has come under specific scrutiny is that of livestock farming due to land use and forms of pollution generated from the industry. However not all forms of livestock have the same level of environmental impacts. In the case of pig farming the level of land use is much lower due to pigs not being grazing animals as such can be kept healthily in smaller scale operations. The main source of pollution comes from trace metals and other chemicals found in pig manure entering the soil and water supply. However, this can be negated through responsible disposal of manure. There can even be environmental benefit through recycling pig manure as organic fertiliser reducing dependence of chemical fertilisers. Another way to reduce the environmental impact of pig farming would be to find uses for pigs outside of meat such way would be to use pigs in disposal of organic waste such as inedible material from crop farmers as well as food waste. Such a practise would help remove a great deal of organic waste from landfills and will help recycle nutrients and energy back into the food chain. Another area would be land management, pig’s natural rooting behaviour can help rotate top soil and remove unwanted plants such as bracken from land reducing the need for machines and thus potential pollution. As a final point more research is required to further synergise industrial practises.


During the 21st century it has become increasingly clear that ecological sustainability is an important factor for the continuation of industries and practises. One industry that has come under particular scrutiny is livestock farming due to waste and pollution caused by it as well as potential environmental destruction. However, livestock farming is very varied between livestock animal’s needs and byproducts of the animals. As such each form of livestock farming must be assessed separately in terms of their impact and sustainability. The purpose of this essay is to look at ways pig farming could be made more ecologically sustainable. In addition to this it will explore some potentially alternate uses for pigs outside of its main use in industry.

Helping negate some impacts of pork production.

In recent decades a greater emphasis has been put on agriculture particularly livestock farming to be more environmentally sustainable with an emphasis on animal welfare. Pork is also a large part of people’s diet particularly in European countries so sustainable pig farming is high on most societies’ priorities. Though due to lack of proper information about pig farming many will simply adopt “politically correct” opinions based on stereotypes for farming models. More environmentally conscious people tend to favour medium to small scale pig farming systems, though many will simply write off livestock farming as unable to reduce impacts in the environment. Though people’s attitudes towards pig farming do not always correlate with statistical purchases of pork products between different demographics. This implies that the populace will not always act on their concerns for the environment or animal welfare (Krystallis. A, et al, 2009).

A study in 2002 stated livestock and crop farming must become more integrated in order to become more sustainable. pig farming specifically needs to have a high level of nitrogen utilisation throughout the system, this includes lower inclusion of protein feeds. This will specifically reduce land use and as a result will lower nitrogen emissions. One way to make pig rearing more efficient and more environmentally friendly would be the use of synthetic amino acids rather than protein-based crops, the one drawback being the cost. Another strategy would be to focus on breeds with naturally high feed conversion rates would help more efficient meat production. This would also reduce environmental costs in addition to locally sourced protein rich food sources for domestic pigs (Eriksson. I. S, 2004). Intensive farming methods are not only harmful to the environment but can also lead to immune deficiencies in piglets. The traditional way around this was to give frequent antibiotics, however this can also be harmful to the cultivation of useful microbes and lead to antibiotic resistant bacteria. Excessive antibiotic use also leads to dysbiosis which can restrict nutrient absorption in the gut. This can significantly reduce growth rates in piglets and thus decrease returns for pig farmers. It is suggested by a study in 2022 that replacing antibiotics with organic acidifiers into a pig’s ration will increase weight gains of the animal and aid in the suppression of pathogenic micro-organisms (Komlatsky. V. I, et al, 2022).

Outdoor pigs are often reared in an arable ley rotation system where they are able to freely graze and their feed is supplemented with commercial feed, normally consisting of cereals. While outdoor reared pig releases more carbon dioxide than indoor pigs the carbon dioxide is offset by sequestration. This will happen to the soil during arable and grazed courses of the rotation when no pigs are present in the fields. Pigs often cause changes to soil due to rooting, feeding and waste production increasing the risk of runoff and erosion of soil. Meanwhile pig’s dung will produce nutrient hotspots through the chemicals in the dung entering the soil. As such it is important to properly rotate fields pigs are kept in to allow for soil recovery. This will ensure pigs are not kept in a field for longer than necessary to ensure minimal soil damage (Benhua. S, et al, 2022). Small and medium scale pig farmers are characterised by ecological systems being disrupted for small amounts of time and restored quickly. Whereas large scale farms and industrial scale pig farming complexes there is often large-scale pollution. The main forms of pollution from farming are water vapour, carbon dioxide, ammonia, hydrogen sulphide, dust and pathogenic microflora (Samarin. G, et al, 2021).

The initial combination of European and Asian pig breeds laid the foundation for the potential for developing more efficiently growing breeds which will be more environmentally friendly. These breeds include: durocs large whites, landraces and hampshires. Use of computer monitoring of livestock nutrition and growth rates could be used for precision livestock farming. Use of precision farming could help minimise waste in livestock farming and reduce both cost and environmental impact. In addition, selective breeding can be implemented to help produce hardier breeds which can flourish in suboptimal climates and conditions. This would be a great boon to certain regions and countries affected by climate change (Rauw. W, et al, 2020).

Use of pigs in food waste disposal

In countries like the USA dry feed systems are predominantly used in pig feeding, high moisture content of all food wastes requires drying out before being converted into commercial swine diets. One reason for this is that moisture content in food waste can increase susceptibility to microbial growth and spoilage and simple thermal heating can remove these risks (Fung. L, et al, 2018). Use of brewery mash as an inexpensive source of pig feed which will provide pigs with necessary calories to stimulate growth with minimal cost. This can both reduce costs of fattening pigs and can assist local breweries by reducing their own waste disposal of alcohol by products and potentially reduce brewery waste entering the environment (Zhichkin. K, et al, 2019). There are several ways a pig’s diet can be altered to reduce environmental impact such as substituting soy beans for pea and rapeseed plants in pig feeds. These substitutions will reduce energy costs of pork production greatly and help reduce the amount needed to sustain pigs. Several proposals were made in 2021 to incorporate environmental impact of feed ingredients in the feed formulation process. This calculation of pig diets has traditionally only too factors like cost into consideration. Other substitutions such as replacing cereals, soy beans and oils with fava beans the environmental cost will go down significantly. However, some of these new diets can negatively affect animal performance and growth rates. As such formulation must recalculate amount of feed given to maintain a healthy growth rate in pigs (Quelen. F. D, et al, 2021).

Conventional swine diets consist on maize and soybeans as energy and protein sources, it is thought food waste could be a substitute for part of cereal grains and plant protein sources. In terms of animal nutrition this could lower costs for food production and recycle otherwise lost nutrients back into the food chain. One factor which could complicate use of food waste in animal diets is variability in its nutrition as well as moisture content which may limit the timeframe that it can be used as animal feed. Incorporating bioactive products from food waste into livestock diets may however provide additional health benefits for humans. Recycling food waste as animal feed could also have additional environmental benefits though reducing amounts of waste disposed in more ways such as landfills. Given food waste accounts for 1/3 of all food production and increasing need for animal feed there is definitely a good reason to start recycling food waste. Utilising feed made from recycled food waste could also lower production cost for raising swine and poultry providing and economic incentive for this practise (Georganas. A, et al, 2020).

Recycling pig waste.

Developing more advanced waste management systems to better suit large scale pig farming to ensure minimal nutrient loss and environmental damage from pig manure. Processing pig manure will help with the production of organic fertilizers for crop farming and biogas (a methane-based fuel) for industrial enterprises (Izmaylov. A, et al, 2022). Pig slurry has often been proposed as an efficient natural fertiliser for crops, particularly humas plants (Deike. S, et al, 2008). In some countries the pig on litter system is used in which pigs are raised on litter bedding (such as sawdust). This allows the pig waste to be composted in situ and allows for nitrogenous compounds to be partially decomposed allowing for removal of offensive odors. Commercial bacterial products are often added to bedding to ensure establishment of initial microbial populations thus ensuring proper composting conditions. The only waste product from this system is spent litter which contain high levels of organic matter and trace elements. This can then be used as a soil conditioner or as a fertilizer which can aid in crop farming (Tiquia. S. M, et al, 1997).

Some studies suggest the use of manure as a byproduct of agriculture can increase organic carbon available in arable land. As well as this, farmers can assist in recycling crop waste back into livestock farming as feed and bedding. These together allow for more efficient carbon sequestering as well as increased agricultural sustainability (Smith. P, et al, 2001). Use of pig manure as a fertiliser is an effective component of crop field rotation and to better increase soil fertility and nutrient use. This will increase efficiency and ensure nitrogen levels are properly recycled back into soil once crops have been harvested and reduce the need for chemical fertilisers (Wilkins. R. J, 2008). One form of pollution generated by pig waste is metal accumulation in soil which can affect the life cycle of various plants and microorganisms. In small doses pig manure is good as a fertiliser, however if manure production exceeds soil capacity it can be pollutive, many of these heavy metals are found in commercial pig feeds. As such it is key to monitor heavy metals levels found in pig feed and ensure pig manure properly disposed of to minimise risk of environmental harm (Mattias. J. L, et al, 2010).

An example of this practise being researched is in China, as one of the largest pork producers, in 2017 it was responsible for 50% of global pork production. However, China’s intensive pig farming methods lead to several environmental issues. This includes excess nitrogen and phosphorus in soil and water pollution from excess manure. However, pig manure is rich in nutrients and organic carbon and thus considered a good raw material for producing organic fertilisers. The main way to create fertiliser from manure is composting, however this is inefficient as it takes time and a great deal of space. Pyrolysis carbonization may be a way to circumvent these problems by converting manure to biochar which is a versatile biomaterial. This material can immobilise contaminants in in water and soil, enhance soil carbon sequestration and improve fertilisation and crop yield and minimise greenhouse gas emissions. However, pyrolysis requires dry feed stock material which is not ideal for fresh pig manure which have high water contents. Hydrothermal carbonisation is a simple ecology friendly wat to convert biomass with high moisture content int cokes under relatively a low temperature. This is promising for producing useful carbon function material from low value waste which can act as a fertiliser and an absorbent for heavy metals with less need for feedstock preparation. This could also reduce risk of manure derived pollutants entering water ways from livestock farming (Song. C, et al, 2017).

Use of pigs in land management.

Bracken is a species of plant which can have a severe negative affect on biodiversity in the UK, which can have numerous negative environmental consequences. It has been suggested that the use of pigs to clear bracken infested land could be viable for several reasons:

• Rooting behaviour may lead to pigs eating bracken rhizomes.

• Distributing litter layer beneath bracken canopy through rooting, trampling or using bracken fronds for bedding allowing for germination of other species.

• Use of energy by bracken to reestablish itself will deplete bracken energy reserves.

A study in 2009 released wild boar into the Caledonian forests to help control its bracken problem and it was shown be effective, after three years bracken population had decreased. Several other studies have shown similar results alongside increased biodiversity in post bracken areas, the only problem being these studies have minimal data sets. Also, these data sets are mostly anecdotal as such more data heavy sets are necessary for a more accurate picture. Another drawback to this would be potential health risks to pigs themselves to possible bracken poisoning. As a whole this shows the potential for pigs to be used as a more naturalistic form of land management. This could also lower environmental impact of land management projects (Henney. J, 2012).


From the studies looked at in this work it is easy to see that there is undeniable environmental impact caused by pig farming. This impact comes from pollutive material being released into ecosystems from pig manure and other waste products and some minor environmental damage through pig rooting behaviour. Though the second for of damage is much more negligible and much more easily controlled through better management of pig husbandry. One point in favour of pig farming is that its pollutive potential is much lower than those of more ruminant livestock. In addition to this much less space is required for pig farming due to a significantly lower dependence on grazing land even in free range farming. Pig farming can also be made much more ecologically sustainable through proper waste management as well as repurposing pig waste to assist other areas such as crop farming. This could assist in reducing environmental impact of crop farming through reducing risk of chemical fertilisers. Pigs can also find purpose in areas outside of meat production such as assisting in organic waste disposal (such as inedible crop products) and more naturalistic land management techniques. This could be a further boon in assisting other areas of industry in becoming more ecologically sustainable. Though for this further research is defiantly needed to iron out inefficiencies and costs. For this to work however greater cooperation is needed between different farming sectors as well as pig farming industries to ensure actual progress can be made.


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I am a Medical Laboratory assistant and part time essayist with an interest in natural history and livestock managent. If you would like to see some of my other work please check here.

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