excreted. Crude
protein levels usually drop by
increments of 2 percent until pigs are consuming a
13-15 percent crude protein diet at finishing.
Concentrations of other nutrients are changed in a
similar fashion.
Pig diets are produced in a variety of ways. Many
producers have on-farm feed mills and mix their own
feed from individual ingredients. Others use homegrown grain
and either a commercial protein
supplement that contains all of the protein, vitamins
and minerals needed or add a protein meal (soybean,
canola, peas, etc.) and a premix that contains only
vitamins and minerals. Finally, some farms purchase
complete rations from feed manufacturers that require
no further processing or mixing.
In addition to feed ingredients, the pork industry uses
large quantities of lumber, steel, concrete, medications and
pharmaceuticals and labor.
Genetics and Breeding
Today’s pigs are bred
and fed to be leaner than the pigs of yesteryear. Compared
with the pigs from the 1950s, today’s model has slimmed down
considerably, with 75 percent less fat. Around World War II,
pigs averaged 2.86 inches of backfat compared with less than
0.75 inches today.
Consumers, and consequently packers, prefer lean
pork, and producers are raising leaner, heavier muscled pigs
to satisfy these demands. The leaner pork is the result of
new technology in hog production |
and superior
genetics. Producers use purebred seedstock of nine major
swine breeds, which are:
• Yorkshire (or Large White),
• Duroc,
• Hampshire,
• Landrace,
• Berkshire,
• Spotted,
• Chester White,
• Poland China and
• Pietrain
Producers also use synthetic lines derived from these
breeds by breeding companies such as PIC, Monsanto
Choice Genetics, Newsham Hybrids, Danbred USA,
Genetipork and Babcock Swine. Virtually all market pigs are
produced by crossing purebred breeds or synthetic lines to
take advantage of heterosis or
hybrid vigor.
Heterosis is a biological phenomenon in which the
offspring of a mating of two separate breeds or lines
performs better than the average of their parents.
Crossbred offspring, such as the pork industry’s
SYMBOL III (described on
the next page) grow faster,
have lower mortality rates and convert feed to meat
more efficiently. Symbol III is a visual image of the ideal
pig.
Rotational breeding systems
involve the successive
use of boars of different breeds and the retention of gilts
that are superior for growth rate, leanness and |
