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 Zierke works with a team of leading genetic consultants with a commitment
to research and development. The focus of Zierke's R&D efforts is the
improvement of pure lines to be used in breeding systems for commercial
pork production. As an originating member of the National Nucleus,
Zierke continually conducts testing of all economically important
traits. The results of this testing are used within two different
monitoring systems to identify potential replacements. A within-herd
system called Herdsman® calculates
Expected Progeny Deviations (EPDs) which are weighted within various
indexes to achieve optimum progress. An across-herd Best Linear
Unbiased Prediction (BLUP) system called STAGES® is used for comparisons
within major breeds across the nation. In addition, Zierke conducts
disciplined, ongoing meat quality research concerning pH, marbling
and color. These results are also used in selecting replacement
animals.
Definitions
The term EPD stands for Expected Progeny Differences, or the predicted
performance of future offspring. It is expressed as a deviation from
the mean of the base group of animals.
The EPD and Indexing systems were developed by the National Swine
Registry and are the center of their STAGES (Swine Testing and Genetic
Evaluation System) program. Understanding EPDs and Indexes is important
to utilizing valuable STAGES data to make genetics buying decisions.
(NBA) Number Born Alive:
Predicts the number born alive for each individual's progeny relative
to an average pig. A sow with an EPD of +.5 would be expected to produce
daughters that would farrow litters with .5 more pigs than an average
sow.
(LWT) 21-Day Litter Weight:
Predicts the 21-day litter weight for an animal's progeny. A sow with
an EPD of +3.4 would be expected to produce daughters which would produce
litters 3.4 pounds heavier at 21 days than the average sow.
(SPI) Sow Productivity Index:
An index for reproductive traits that combines number born alive and
21-day litter weight. Ancestral data and a sow's lifetime data are
included in her SPI.
(DAYS) Days/230:
Predicts the performance of offspring of an animal. A boar with an
EPD of -3.0 would be expected to produce progeny that would reach 230
pounds 3 days faster than an average boar.
(BF) Backfat:
Predicts backfat of the offspring. A boar with an EPD of -.04 would
be expected to sire pigs .04 inches leaner than an average boar.
(MLI) Maternal Line Index:
This index places greater emphasis on the reproductive traits. Selection
of this index is appropriate when the majority of the pigs are sold
as either replacement gilts or to a gilt producing herd.
(TLI) Terminal Line Index:
This index combines growth and backfat only
and is appropriate to use when selecting boars for use as terminal
sires in a crossbreeding program.
(LEA) Loin Eye Area:
Loin Eye Area measurement in square inches, adjusted to 250 pounds
live weight. The EPD for LEA is not reported, but is used in the calculation
of an EPD for Pounds of Lean (Lbs.).
(LBS) Pounds:
Predicts pounds of fat free lean of the offspring of
an animal. A boar with an EPD of 1.5 would be expected to produce progeny
that would yield 1.5 more pounds of lean than an average boar.
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