Genetic Disorders
From 2008 to 2010, The American Angus Association discovered several genetic disorders in the breed referred to as "AM," "NH" and "CA." A test for dwarfism was discovered several years before 2008. A very small number of Black Angus, some Red Angus, Holsteins, Simmental and Hereford as well as humans carry OS also known as Osteopetrosis or "Marble Bone."
The four recessive defects can produce affected calves. A "recessive defect" requires both parents to carry the recessive gene to have a calf that is "affected" or shows the defect, and then only an average of one in four will show the defect even with both parents carrying the defective gene. The four recessive defects that can be tested for in the Black Angus breed are: Arthrogryposis Multiplex (AM) referred to as curly calf; Neuropathic Hydrocephalus (NH) sometimes known as water head; Contractural Arachnodactyly (CA) formerly referred to by the name of “Fawn Calf Syndrome;" and dwarfism. DNA testing is now available for AM, NH, CA and one type of dwarfism. AM, CA and dwarfism are not deadly to the calf; however, calves affected with any one of these defects may be easier prey to predators and may also live a shortened life due to other complications. An affected NH calf will generally be born dead; however, an affected calf with this defect is very serious because the mother cow can die during an unsupervised birth, or she may require a cesarean section due to the enlarged head of the calf. However, both parents need to carry the recessive gene for any calf to be affected.
Because of these defects, the American Angus Association has chosen to remove the carrier animals from the breed and has instituted a somewhat involved program to remove the defective animals, but especially their offspring, from the breed. The American Angus Association has made rules to govern AM, NH and CA so that by January 1, 2012 for AM, and June 15, 2012 for NH, no Angus will be registered that is a carrier. After that time, owners may use carrier bulls or carrier cows in their own herds but cannot register offspring unless the offspring are tested defect free. This extended time period allows breeders to recover their registered herds by replacing carrier mothers with non-carrier daughters. An animal designated as a carrier of dwarfism will not have offspring registered.
Read more about this topic: Black Angus
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