PIGS 101

Pig Terminology:

  • Barrow – a male castrated before it reaches sexual maturity
  • Boar – a mature male used for breeding purposes
  • Farrow – to give birth to piglets
  • Feed Efficiency (Feed Conversion Ratio) – the amount of feed consumed to produce a pound of meat
  • Feeder Pig – a pig weighing between approximately 40 and 60 pounds
  • Fetal Pig - unborn pig
  • Finish – to feed a pig until it reaches a market weight, approximately 180-300 pounds
  • Gilt – a young female that has not farrowed her first litter
  • Nursery Pig – any pig weighing approximately 10 – 40 pounds
  • Piglet – newborn pig, young or juvenile pig
  • Sow – a mature female that has farrowed at least one litter
  • Wean – to separate pigs from the sow

There are four primary stages in porcine production:

Breeding and Farrowing

  • Gilts are bred when they are approximately 6 to 8 months old.
  • Sows are bred approximately 3 days after piglets are weaned.
  • The gestation period for pigs is approximately 114 days.
  • Pigs farrow litter sizes ranging from 6 to 13 piglets.
  • The average birth weight per piglet is approximately 2 – 4 lbs.
  • Young pigs are introduced to regular pig feed at 10 – 12 days of age.


  • Pigs are generally weaned at three to four weeks of age.
  • Weaned pigs weigh approximately 10 to 15 pounds.
  • Weaned pigs are typically moved to a nursery and raised until they reach a weight of approximately 40 to 60 pounds.


  • Pigs are moved to a finishing barn at approximately 8 weeks of age and approximately 40 – 60 pounds.
  • Pigs will remain at a finishing barn until they reach market weight of approximately 180 to 300 pounds.

 Abattoir Processing

  • When pigs reach approximately 180 to 300 pounds, producers sell them to an abattoir.
  • Market hogs may be 5 to 6 months old.
  • It takes approximately 10 months after successful breeding for pigs to reach market weight.

Pricing and Production

Pig producers need approximately 18 to 20 months to alter the supply chain once a decision is made to increase or decrease production. The times referenced below are all approximate times.

  • Gilt reaches maturity to breed – 6 to 8 months
  • Gestation – 4 months
  • Farrowing Barn – 1 month
  • Nursery – 2 months
  • Finish – 3 - 4 months

Feed is the major input to the pork production process, accounting for about two-thirds of costs. The average whole-herd feed conversion ratio (pounds of feed required per pound of live weight produced) for the U.S. pork industry is 3.4 to 3.6 and continues to improve. For example, it takes 900 pounds of feed to raise a 250lb pig (3.6 x 250).

Pig prices vary cyclically and seasonally. Cyclical variation is caused by the time lags inherent to biological production. When prices are high, more sows are bred and more pigs are produced; however, these pigs will not reach the market until approximately 10 months after they are conceived. When they do, supplies increase and prices fall, thus causing a price cycle. Seasonal variation is caused by changes in production efficiency due to weather and different demand levels.


Most housing for pigs has slotted floors that allow the pigs’ waste to fall through into a holding pit or gutter. This keeps the floors drier and cleaner and makes it easier to provide the correct environment to keep pigs comfortable and productive, as well as minimizing disease and biohazards.