According to ERS (USDA), U.S. hog production has become increasingly concentrated in fewer, larger, and more specialized operations over the last two decades.
Hog farm productivity growth slowed considerably after 2004 for specialized hog finishing operations. With most hogs now grown on very large operations and with most productivity-enhancing innovations widespread, rapid productivity gains experienced prior to 2004 will likely remain unmatched, absent further technological innovation.
The number of U.S. hog farms declined by more than 70 percent over the past two decades while hog production rose by more than 30 percent. The result has been an industry with larger hog enterprises, increased specialization in a single phase of production, greater reliance on purchased feed rather than feed grown on the farm, and an increased reliance on formal contracts that connect farmers, hog owners, and packers to coordinate production.
Traditionally, hogs were produced on farrow-to-finish operations that managed production from breeding to sale for slaughter. Today, most hog operations specialize in one of the three major life-cycle phases of production: farrow-to-wean (breeding to weaning), wean-to-feeder (weaning to a 30-80 pound feeder pig), or feeder-to-finish (feeder pig to slaughter weight). In 1992, 65 percent of market hogs came from farrow-to-finish farms. By 2009, only 20 percent came from farrow-to-finish farms and 73 percent of market hogs were produced on specialized feeder-to-finish farms.
Monday February 2, 2014/ ERS-USDA/ United States.
http://www.ers.usda.gov