Hogs are produced in three types of specialized enterprises:
- Farrow-to-finish operations raise hogs from birth to slaughter weight, about 240-270 pounds.
- Feeder pig producers raise pigs from birth to about 10-60 pounds, then generally sell them for finishing.
- Feeder pig finishers buy feeder pigs and grow them to slaughter weight.
Some overlap exists in enterprise type. For example, farrow-to-finish operators may sell or buy feeder pigs if their feed production is smaller or larger than their own production needs. However, most producers use only one production system.
The Biological Hog Cycle
The biological hog cycle is longer than that of broilers, but shorter than for cattle. (The economic hog cycle refers to the peaks and valleys in hog inventories over time, while the biological hog cycle refers to the biological time lags involved in hog production). A sow can produce an average of slightly more than two litters per year, each consisting of an average of nearly nine pigs. Production of hogs has consisted of five different phases: farrow-to-wean, feeder pig or nursery, finishing, breeding stock, and farrow-to-finish. Swine biology may be thought of as a flowing, cyclical process.
Source: Dr. Paul Pitcher and Sandra Springer, University of Pennsylvania School of Veterinary Medicine, 1997.
It takes about 32 weeks, from birth to breeding age, before a gilt (a female hog that has not farrowed--that is, given birth) is ready to reproduce. The reproduction process begins with the mating of a gilt capable of conception and a boar (male hog) or by artificially inseminating the gilt with semen from a desired boar. Once the gilt has been bred successfully, she will farrow an average of nine piglets (young pigs) in approximately 16 weeks. A sow (adult female hog that has farrowed at least once) can be bred again shortly after pigs from the previous litter are weaned.
In a farrow-to-finish operation, 22-26 weeks (starting at birth) are required to grow a pig to slaughter weight. Sows nurse their piglets for an average of 2-3 weeks before they are weaned (separated from the sow). This is the farrow-to-wean phase of hog production. Weighing an average of 10-20 pounds, the weaned pigs are moved on to the next phase of production known as wean-to-feeder pig. During this phase, young pigs are fed rations varying in protein content until they reach an average weight of 20-60 pounds. From the feeder pig stage, the animals enter an intense feeding stage and remain there until they reach a desired weight, ranging from 240-270 pounds. Operations of this type are known as the feeder-pig-to-finish phase.
Hog production phases and completion times*
Breeding and gestation of producing female
Birth to breeding age
Length of time
8-9 newborn pigs every 6 months
*Phases and times are reasonable examples only. Actual industry values will vary by season, phase of the production cycle, region, and firm.
Most hog producers use some type of confinement production, with specialized, environmentally modified facilities. Confinement production allows year-round production by protecting hogs from seasonal weather changes, while reserving productive land for crops. Central farrowing houses shelter sows that give birth and care for their young until they are weaned. After being weaned, baby pigs enter the pig nursery where conditions ease the transition between weaning and the growing-finishing stage. After reaching a weight of 20-60 pounds, the pigs are either sold to a feeder-pig finisher or transferred to the growing-finishing house, where they are grown out for slaughter.
One of the most striking features of the U.S. hog industry has been the rapid shift to fewer and larger operations, associated with technological change and evolving economic relationships among producers, packers, and consumers. Over the past 15 years, the number of farms with hogs has declined by over 70 percent, as individual enterprises have grown larger. U.S. hog operations tend to be heavily concentrated in the Midwest--Iowa and Southern Minnesota, particularly--and in eastern North Carolina.
Large operations that specialize in a single phase of production have replaced farrow-to-finish operations that performed all phases of production. The use of production contracts has increased. Operations producing under contract are larger than independent operations and are more likely to specialize in a single phase of production. These structural changes have coincided with efficiency gains and lower production costs. Most of the productivity gains are attributable to increases in the scale of production and technological innovation. (For more information, see The Changing Economics of U.S. Hog Production, Economic Research Report, December 2007.)