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Genetic Defects and IBEP Bulls
Currently, six 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. Osteopetrosis (OS) is found in Red Angus cattle. Pulmonary Hypoplasia
with Anasarca (PHA) and Tibial Hemimilia (TH) are found in Shorthorn and other breeds. The
Angus Association also tracks Developmental Duplication (DD) and the Myostatin nt81 Gene
Deletion (M1), also known as Double Muscling, although these are not considered to be lethal
conditions.
In the IBEP 2013 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, M1F, OSF (tested free), or have no
carrier ancestors for AM, CA, NH, M1, or OS.
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.
