Cholesterol Deficiency (CD)
Cholesterol deficiency (CD) is a recessive genetic disorder in Holstein cattle that affects lipid metabolism and causes young calves to die, usually within 3 weeks-6 months of age as a consequence of chronic diarrhea and failure to thrive. Affected calves show very low levels of cholesterol (severe hypocholesterolemia). The genetic defect traces back to bull Maughlin Storm born in 1991. Molecular analyses identified the mutation responsible for CD as a 1.3Kb insertion of a transposable LTR element (ERV2-1) in the coding sequence of the apolipoprotein B (APOB) gene that renders the APOB protein non-functional. The APOB protein is a key component in a system responsible for transporting fat molecules, including cholesterol, around the body and into cells. Carriers of CD appear to be normal and show no clinical signs of malabsorption despite a reduced level of cholesterol when compared to non-carriers. A DNA diagnostic test for the APOB mutation has been developed by researchers in Switzerland to determine whether animals are free of the mutation, are CD-carriers (1 copy of the mutation) or CD-affected (2 copies of the mutation).
The VGL offers a test specific for the Holstein CD mutation. Breeders can use results from the test as a tool for selection of mating pairs to avoid producing affected calves.
Results reported as:
|N/N||Normal, animal does not have the CD mutation|
|N/CD||Carrier. Animal has 1 copy of the CD mutation. Breeding to another carrier will produce 25% affected calves.|
|CD/CD||Affected. Animal has 2 copies of the CD-mutation.|
Note: This test is specific for the mutation in the apolipoprotein B (APOB) gene associated with cholesterol deficiency in Holstein cattle.
Menzi F, Besuchet-Schmutz N, Fragnière M, Hofstetter S, Jagannathan V, Mock T, Raemy A, Studer E, Mehinagic K, Regenscheit N, Meylan M, Schmitz-Hsu F, Drögemüller C. A transposable element insertion in APOB causes cholesterol deficiency in Holstein cattle. Anim Genet. 2016 Apr;47(2):253-257
Gross JJ, Schwinn AC, Schmitz-Hsu F, Menzi F, Drögemüller C, Albrecht C, Bruckmaier RM. Rapid Communication: Cholesterol deficiency-associated APOB mutation impacts lipid metabolism in Holstein calves and breeding bulls. J Anim Sci. 2016 Apr;94(4):1761-1766.
The Melanocortin-1 Receptor gene (MC1R), also called Extension (E), controls black and red pigment production in cattle. Holstein cattle have another gene, Dominant Red, which overrides MC1R and produces dominant red pigment. The VGL offers 2 DNA tests to help Holstein breeders select for their preferred color variants.
MC1R includes Black/Red (Telstar)
The four alleles of the MC1R gene are dominant black (ED), Black/Red (EBR), wild type red (E+) and recessive red (e). Dominant black (ED) is dominant to the other three alleles and animals with ED are black and white. Black/Red, also known as Telstar, (EBR) results in red color at birth which changes to black at a young age, usually by 3-6 months. Wild type red (E+) produces cattle with red and white coloration that may appear darker towards the extremities of the body, especially as the animal ages. Two copies of the recessive red (e) allele result in red color. The order of dominance is ED>EBR>E+>e.
Note: The test for Black/Red color is based on a linked marker associated with the phenotype. Research is ongoing to find the causative mutation for Black/Red.
Results reported as:
|ED/ED||Black and white. This animal cannot produce red offspring. *|
|ED/EBR||Black and white, carrier of Black/Red. *|
|ED/E+||Black and white, carrier of wild type red. *|
|ED/e||Black and white, carrier of recessive red. *|
|EBR/EBR||Black/Red. This animal cannot produce true red offspring. *|
|EBR/E+||Black/Red, carrier of wild type red. *|
|EBR/e||Black/Red, carrier of recessive red. *|
|E+/E+||Wild type red and white.|
|E+/e||Wild type red and white, carrier of recessive red.|
|e/e||Recessive red and white. When bred to another e/e will produce only red offspring.|
* In the absence of Dominant Red
Dominant Red (Variant Red)
Dominant Red, as the name implies, is a dominant red color that occurs in Holstein cattle. The Dominant Red gene is independent from MC1R, a major gene controlling black and red color in Holstein. Dominant Red color is increasing in popularity among breeders. The mutation that causes Dominant Red has been identified by a team of researchers from the US, Canada and Sweden. The VGL offers a test for Dominant Red which allows breeders to identify homozygous (2 copies) animals which will always produce Red and White offspring. The Dominant Red test is also useful in determining if an animal is red due to both MC1R and Dominant Red.
Results reported as:
|N/N||No copies of Dominant Red present. Color is dependent on MC1R genotype.|
|N/DR||1 copy of Dominant Red present. Animal is red and white and 50% of offspring are expected to be red and white.|
|DR/DR||2 copies of Dominant Red present. Animal is red and white; all offspring are expected to be red and white.|
Dorshorst B, Henegar C, Liao X, Sällman Almén M, Rubin C-J, Ito S, et al. (2015) Dominant Red Coat Color in Holstein Cattle Is Associated with a Missense Mutation in the Coatomer Protein Complex, Subunit Alpha (COPA) Gene. PLoS ONE 10(6):e0128969. doi:10.1371/journal.pone.0128969.