Domestic Pig Facts

Scientific Name: Sus scrofa domestica

Young piglet at pig breeding farm
Young piglet at pig breeding farm.

kadmy / Getty Images

The 600+ breeds of the domestic pig (Sus scrofa domestica) on our planet today are descended from the wild boar, Sus scrofa, a process that occurred at least twice in different places between 9,000–10,000 years ago.

Domesticated pigs are bred for human consumption. Pork and pork products make up the largest percentage of meat and poultry consumed in the world, representing over 40% of the world's meat and poultry eaten in 2017. 

Fast Facts: Domestic Pig

  • Scientific Name: Sus scrofa domestica
  • Common Name: Pig, hog, swine
  • Basic Animal Group: Mammal
  • Size: 7–8 feet long, 3.7–4.7 feet high
  • Weight: 600–1,000 pounds or more
  • Lifespan: 6 to 10 years 
  • Diet: Omnivore
  • Habitat: Pastures, farms, and commercial buildings on all continents except Antarctica
  • Population: Estimated at two billion (nearly 1 billion are slaughtered each year)
  • Conservation Status: Sus scrofa domestica has not been evaluated by the IUCN.

Description

There are over 600 different breeds of domestic pig (Sus scrofa domestica) extant in the world. The top five most recorded in North America are American Yorkshire, Duroc, Berkshire, Hampshire, and Landrace. The most commonly produced is the American Yorkshire, a version of the English Large White pig, developed in 1761 and first imported to the U.S. in 1830. 

Yorkshires are white in color and quite muscular, with a high proportion of lean meat and low back fat. Its body is covered in fine hair, and they have long snouts and erect ears. Depending on the breed, adult pigs range from seven to eight feet in length and weigh between 600 and 1,000 pounds. There are many smaller pig breeds as well. 

All domestic pigs belong to the family Suidae, order Artiodactyla, kingdom Animalia, class Mammalia, phylum Chordata. 

Yorkshire pigs on an organic farm.
Yorkshire pigs on an organic farm. Agnormark / iStock / Getty Images Plus

Habitat and Distribution

Domestic pigs are found on all continents of the world, excepting Antarctica. As of 2010, the largest producers of pigs include China (about 500 million each year), US (64 million), Brazil (40 million), Germany (27 million), Vietnam (27 million), and Spain (25 million).

Pigs are kept in pens, in facilities, and in open farm fields and forests, and the farms range in size from facilities with tens of thousands of animals to subsistence farms of one or two.

Diet and Behavior 

Pigs are omnivores and they will eat anything, meat and plants both. The digestive system of pigs is such that it can also consume bulky foods with high levels of roughage. If kept in a well-fenced field they will eat all of the plants and grass, digging into the ground to consume the roots as well. Farmers put a ring into a pig's nose to keep it from digging up the plant roots. 

Domestic pigs cannot be raised solely on pastures. Their diets need to be supplemented with vegetables, corn, or other crops, and they can be fed table scraps. A permanent pasture to keep pigs is one that stays planted to grass or legumes such alfalfa and clover, and/or perennial grasses such as orchard grass, timothy, and bromegrass. 

Pigs grow well on large, open-air concrete platforms, in pens with a partial-solid floor area for resting and feeding and another area with a slatted floor so manure drops through and keeps the pen clean, or on pastures supplemented with grains. They require plenty of clean water every day. Pigs are gregarious and can be quite social: but males can be aggressive and farmers typically castrate them at an early age. 

Free Range Pastured Domestic Pigs
Free range pigs grazing in an organic ecological farm. RonyZmiri / iStock / Getty Images Plus

Reproduction and Offspring

Pigs have male and female sexes, and in most modern facilities, reproduction is controlled at all steps, inducing heat in females, artificial insemination, and weaning. Most breeds of pig reach puberty (come into heat) at 5 months, but sources recommend that females not be bred until 6 months of age. 

Non-pregnant sows naturally come into heat every 21 days throughout the year, and the heat lasts between 8 and 36 hours. During that period, impregnation occurs either artificially, or by the farmer introducing a boar. Once impregnated, sows give birth after three months, three weeks and three days. Sows make a nest within 24 hours before giving birth, and farrowing usually lasts between 2 to 3 hours. Healthy sows give birth to between 10 and 13 piglets twice a year.

Without coaxing, piglets immediately search for an available teat on their mother, starting to feed within an hour of their birth. They subsist on mother's milk alone for 2–3 weeks, then begin taking solid food. They can continue to take some milk until about 7 weeks, but farmers can wean them as early as 4 weeks. Males pigs are typically castrated at 2–3 weeks of age.

Mother pig feeding piglets
Curious pigs in Pig Breeding farm in swine business in tidy and clean indoor housing farm with pig mother feeding piglet. Chayakorn Lotongkum / iStock / Getty Images Plus

Conservation Status

In 2007, the Food and Agricultural Organization of the United Nations (FAO) listed over 742 specific breeds of domestic pig in the world. Of those, 137 were listed as extinct and 130 were listed as endangered. The International Union for Conservation of Nature (IUCN) does not list Sus scrofa domestica at all but does include nine other (non-domesticated) Sus species in the listings as Vulnerable, Critically Endangered, Endangered, or Extinct (Indo-Chinese warty pig).  

Sources