Nearly 70 percent of hogs in the U.S. are sold to pork
slaughter companies (packers) under pre-arranged marketing contracts,
up from 11 percent in 1993. Marketing contracts between packers
and hog producers typically specify the quantity of hogs to be purchased
on specified dates and places, and provide hog producers a secure
outlet and specific pricing terms. Many of these contracts awarded
price premiums for carcass leanness and weight, providing strong
incentives for producers to raise lean hogs needed for the lower
fat meats demanded by consumers. From 1992 to 2002, the percentage
of lean muscle of a typical pork carcass rose from 49.5 to 55.5
percent.
But this leanness came at a cost. The genetic lines
that produced leaner hogs were often carriers of the “stress”
gene, which was linked to a condition referred to as “pale,
soft, and exudative” (PSE). PSE pork—which is disliked
by packers, retailers, and consumers—has a very light color,
soft texture, and is subject to fluid loss. Controlling the PSE
condition proved to be difficult because packers must be able to
measure and reward producers for reducing PSE-related attributes.
However, indicators of the PSE condition could not be readily measured
at high-speed processing lines that slaughter 1,000 hogs per hour.
In addition, by the time PSE problems become apparent (20-24 hours
postmortem), the identity of the producer may have been lost.
Packers turned to marketing contracts to maintain incentives
for producing leaner hogs and, at the same time, control PSE-related
attributes. These marketing contracts strove to limit PSE problems
by specifying and monitoring input requirements—most importantly
genetic lines. How hogs are handled also influences PSE. For example,
minimal force while moving hogs, nonslip loading ramps, and less
crowding of hogs while on the way to the packing plant all make
for less stressed hogs.
While considerable progress has been made in breeding
out the stress gene, two pork quality audits revealed that the PSE
condition actually worsened—rising from 10.2 percent of slaughter
hogs in 1992 to 15.5 percent in 2002. This suggests hog-handling
problems may have become an important contributor to PSE-related
problems. Some large pork companies stipulate in their marketing
contracts that producers raise hogs in a humane manner or in a way
that optimizes pork quality.
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