The spring 2007 International Limousin Genetic Evaluation marks
the beginning of the fifth year that the University of Georgia (UGA)
has used multibreed genetic-prediction technology. Of the six
largest U.S. beef breeds, only Limousin and Simmental use
multibreed evaluation technology when calculating expected
progeny differences (EPDs). For Limousin breeders and commercial
users, that is significant because EPDs for all animals – from
all breeds and breed crosses represented in the evaluation – are
directly comparable. The technology makes selection and
crossbreeding with Limousin and Lim Flex® genetics easier and
more effective than using EPDs from single-breed evaluations.
Components
The North American Limousin Foundation (NALF) laid the
foundation for its multibreed genetic evaluation more than a
decade ago, when it began recording pedigree information for the
other breeds used in upgrading programs. That paved the way for
introduction of the Lim Flex hybrid, which has resulted in
NALF’s recording pedigree information for more than 10,000 head
of registered Angus, Red Angus and other animals. Accurate
pedigree information for several generations – from whatever
breed – is the basis for multibreed genetic connectedness and
evaluation.
Multibreed genetic evaluations account for differing genetic
merit between breeds. To account for known individual-animal
differences in genetic merit for non-Limousin animals, NALF
works with the American Angus Association (AAA) and the Red
Angus Association of America (RAAA) to incorporate EPD and
accuracy information for those sires into its multibreed
evaluation. Hence, EPDs for Lim Flex animals include each
breed’s pedigree information, EPDs and accuracies, and the
animals’ own performance and contemporary-group data.
Differences in gene frequency (among mates) and through dominant
gene action (for traits like expressed fertility, longevity and
pounds of calf weaned per cow exposed) create heterosis. Animals
with heterozygous genotypes affecting the trait of interest
“outperform” animals with more homozygous genotypes. Typically,
heterosis affects lowly heritable traits more favorably than it
does highly heritable traits.
Commercial users and hybrid-seedstock producers should recognize
that heterosis, or nonadditive genetic merit, is economically
important and must be “recreated” through mating sires and dams
that differ in gene frequency (that is, breed composition).
Similar to most single-breed genetic evaluations, multibreed
genetic-prediction technology accounts for all relationships
among animals, genetic relationships between correlated traits,
selection and factors like nonrandom mating.
More to Learn
Besides EPDs and accuracies for hybrid and straightbred animals
that are directly comparable, the most valuable byproduct of
multibreed evaluation is the comparative data generated between
breeds. More specifically, the UGA multibreed evaluation for the
NALF herdbook produces EPDs for registered Angus and Red Angus
animals. Theoretically, those multibreed EPDs might be even more
informative than the EPDs from their own respective single-breed
evaluations because they incorporate their Angus and Red Angus
external EPD and accuracy information along with all progeny
information for animals exclusively in the NALF herdbook.
NALF prints EPDs and accuracies for Angus and Red Angus animals
on its performance records. Lim Flex breeders can contact NALF
if they want UGA’s multibreed EPDs for specific Angus and Red
Angus sires. If the EPDs are not available, it is because the
animals are not yet on file with NALF or have not yet gone
through its multibreed genetic evaluation. For those animals’
offspring to get multibreed EPDs, breeders must submit both the
pedigree information for the Angus or Red Angus sire or dam and
progeny information before June 15 or Nov. 15.
Look Into the Future
The National Beef Cattle Evaluation Consortium (NBCEC), composed
primarily of the three universities that conduct genetic
evaluations (UGA, Colorado State University and Cornell
University), recently combined the herdbooks of more than 15
breeds, including more than 14 million animals, and computed
experimental multibreed EPDs. That effort proved large-scale
multibreed genetic evaluations are technologically possible.
At least two obstacles to routine, large-scale, multibreed
evaluations remain. The first is development of a sophisticated
data-management infrastructure that facilitates fast, efficient,
repeatable, automated data assembly; preparation for genetic
evaluation; storage; and dissemination of results.
Second, all the breed associations involved in such an effort
must select a common base, or zero point, upon which to express
the EPD for each trait. That is necessary for all EPDs from such
an evaluation to be easily and directly comparable and to have
maximum usefulness for commercial producers in selection and
crossbreeding.
NALF is committed to evaluating Limousin and Lim Flex seedstock
with the most sophisticated technology available and making it
applicable to as many seedstock animals as possible. In the
meantime, remember you can compare directly the EPDs for all
animals in the NALF and Canadian Limousin Association (CLA)
herdbooks, including fullbloods, purebreds, Lim Flex animals and
those of other breeds. If you would like to compare EPDs from
animals in the Limousin evaluation to animals in other
evaluations, contact the NALF office for the most recent
across-breed EPD-conversion factors, which the U.S. Meat Animal
Research Center (MARC) updates annually. |
