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Genetic Defects and IBEP Bulls
Currently, several lethal genetic defects which have DNA tests are being tracked by breed
associations. Arthrogryposis Multiplex (AM), formerly called Curly Calf; Contractural
Arachnodactyly (CA), formerly called Fawn Calf; and Neuropathic Hydrocephalus (NH) are
found in Angus cattle. Alpha-Mannosidosis (MA) and Osteopetrosis (OS) are found in Red
Angus cattle. Pulmonary Hypoplasia with Anasarca (PHA) and Tibial Hemimilia (TH) are
found in Shorthorn and other breeds. Some non-lethal genetic defects are also tracked. The
Angus, Red Angus, and Simmental Associations track Developmental Duplication (DD); the
Angus Association tracks Myostatin nt81 Gene Deletion (M1), also known as Double Muscling;
and the Hereford Association tracks Ideopathic Epilepsy (IE), Dilutor (DL), and Hypotrichosis
(HY).
In the IBEP 2015 Winter Test, bulls had their status checked by their breed association.
Any bulls which were potential carriers, or had unknown ancestry and were considered to be
from a risk population, were tested to determine their genotype for the appropriate traits.
All bulls in the IBEP sale are AMF, CAF, NHF, MAF, OSF, IEF, DLF, or HYF
(tested free), or have no carrier ancestors for those defects.
Bulls that were tested free are
noted with a suffix appended to their registration number.
Bulls which were potential carriers of DD were tested, and their status is noted in the
catalog. Bulls are identified in one of three ways, with a DD suffix appended to their registration
number.
Suffix:
Means this:
DDF
Bull has been DNA tested and is free of DD. The bull can be used
with no risk of DD affected offspring.
DDC
Bull has been DNA tested and is a known carrier of DD. The defect
will be transmitted to 50% of calves, so it is best to use these bulls
in a commercial operation, where no replacements will be kept.
(no suffix appended)
Bull is not a descendent of a known carrier, or his ancestors have
been tested free of DD. The bull is not suspected to carry DD and
can be used for breeding with no increased risk of the defect.
There are five DDC bulls in the sale. Others are either tested free or are not potential
carriers.
There is one bull who is a potential carrier of M1. He is identified as M1P. His status
was set by the American Angus Association late in the test, without time to have him tested.
Because the carrier ancestor is many generation back in his pedigree, it is unlikely that the bull is
a carrier of M1.
