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Pork and chicken production

In 2017 global pig meat production reached 120 million tonnes. China is the major producer at 54 million tonnes, followed by the EU with 24 million, the USA with 11 million, Brazil and Vietnam and Russia with around 3 million tonnes [1]. Out of the five top producers all of them met their national demand except China, which relied on imports to maintain stock (EU pork accounted for 63% of China’s imports in 2018) [2].

Map of world showing pork production: 9% USA, 20% EU, 3% Brazil, 3% Vietnam, 45% China, 3% Russia

Figure 1: Global pork production © University of Reading

Global chicken meat production was 109 million tonnes in 2017 of which the USA accounted for 19 million tonnes. Brazil along with China and the EU produced approximately 13 million tonnes each, followed by Russia at 4.4 million and India at 3.5 million tonnes [3]. For chicken meat the top producer countries are also the main exporters to the global market [2].

Map of world showing chicken production: 17% USA, 12% EU, 12% Brazil, 3% India, 12% China, 4% Russia

Figure 2: Global chicken production © University of Reading

As we saw in Step 3.4, cows, sheep and goats are ruminants which means they have an adapted digestive system allowing them to thrive on high fibre feeds such as grass and hay. Pigs and chickens are different. They are what we call ‘monogastric’ which simply means ‘one stomach’. Humans are also monogastric.

Monogastric animals have a simple digestive tract, although birds do differ from mammals as shown below. Illustration of a pig's organs. From front to back: Stomach, Duodenum, Jejunum, Ileum, Cecum, Colon, Feces

Figure 3: Illustration of the pig’s digestive tract Image provided by Holman, Devin B., Brian W. Brunelle, Julian Trachsel, and Heather K. Allen. “Meta-analysis to define a core microbiota in the swine gut.” MSystems 2, no. 3 (2017): e00004-17 under CC BY 4.0

Illustration of a chicken's organs. From front to back: Crop, Proventriculus, Gizzard, Liver, Duodenum, Pancreas, Small Intestine, Ceca x2, Colon, Cloaca

Figure 4: Diagram of a bird’s gastric system. http://www.poultryhub.org Source © ErikBeyersdorf CC BY-SA 3.0

To be healthy and productive, monogastric animals require a diet that is higher in energy and protein and lower in fibre than ruminants. High energy and protein feeds for pigs and chickens include grains, maize and soybeans, which are also common constituents of the human diet. Buying in feed is the biggest cost for a pig (approx. 80%) or chicken farmer (85%) [5].

How pork is produced

As for beef, there are two contrasting approaches to pork production, indoor and outdoor, depending on where pigs are born and reared. However, a combination of approaches is also used [6]. Factors that influence a farmer’s choice include geographical location, economics, and consumer demands. Pig production consists of four main phases: breeding, farrowing and weaning, nursery, and growing/finishing [7].

In ‘outdoor reared’ pork, pigs spend approximately 50% of the production cycle outdoors, with the finishing phase usually taking place inside straw-based barns [8]. Standard pork tends to come from pigs that are housed indoors throughout the entire production cycle. In this video, a pig farmer discusses why pigs are often raised indoors, today.

This table summarises some key features of indoor and outdoor systems:

Breeding herd: sows and boars Indoor system Outdoor system
Farrowing phase: Birth of piglets. Weaning at ~3 weeks Sows give birth and suckle piglets indoors in specialised farrowing accommodation Sows give birth and suckle piglets outside, with access to a hut and outdoor area
Nursery piglets: For 6-8 weeks post weaning Piglets are raised in a hygienic indoor environment with controlled temperature and airflow, reducing disease risks and maximising growth rates Piglets are reared in a more natural outdoor environment requiring less investment in infrastructure. Lower growth rates are achieved. Pigs may exhibit more natural foraging behaviours.
Grower and finisher pigs: Pigs moved to the grower and finisher system for further 16-18 weeks Finishing barns accommodate pigs for continuous growth. Optimising feeding strategies, the environment and husbandry leads to higher productivity and faster finishing. Pigs are provided with specialised feed , shelter and monitoring. Outdoor pigs take longer to finish than those in indoor systems.
Pigs slaughtered: Typically at 26-28 weeks of age Pigs are ready for slaughter at approximately 110 kg Pigs are ready for slaughter at approximately 110 kg
Table 1: Indoor and outdoor systems of rearing pigs

Efficiency in pork production

As for all livestock farming, the efficiency of a farm can be calculated in many ways, eg

  • the output per unit area,
  • kg of meat output per kg feed input,
  • numbers of offspring produced per female per year [6] [10] [11].

In pork production, farmers measure their pig herd’s performance in:

  • piglets born per sow per year,
  • finished pigs per sow per year (considers pig mortality),
  • average carcass weight of slaughtered pigs.

Farmers combine the data they collect to evaluate which aspects of herd management need attention in order to improve animal health and husbandry, as well as to cut costs.

If we just consider the feed conversion efficiency, as mentioned in Step 3.4, on average to produce 1 kg of pork, 3.6 kg of feed is needed, and to produce 1 kg of chicken, 2.2 kg of feed is needed. This means that monogastrics such as pigs and chickens have a better feed conversion efficiency than ruminants such as beef cattle and lamb.


As the cost of feed is so significant for pig and chicken farmers, they need to maximise the efficiency with which the animals use the feed for growth [11]. Soon after antibiotics were mass produced in the 1950s, small amounts were added to the feed of pigs and chickens to manage gut health and promote increased feed efficiency and growth [12]. However, with the increasing global threat of antibiotic resistance, feeding antibiotics to any farm animal for growth promoting effects was banned in Europe in 2006, although it is still common practice in some countries [13] [14]. Animal scientists are now developing safe alternatives and have focussed their research on better understanding the biology of the gut in pigs and chickens, to find ways of improving their health without reliance on antibiotics [15]. Sick animals still receive antibiotic treatment if appropriate but focussing on strategies that promote overall animal health means therapeutic antibiotic use is reduced as well.

References can be found under the ‘Downloads’ heading at the bottom of this Step.

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Explore How Farmers Produce Food Sustainably

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