The Melanocortin-1 Receptor gene (MC1R), also called Extension (E), controls black and red pigment production in cattle. In Holsteins, there are four known variants including Black/Red (Telstar).
Cholesterol deficiency (CD) is a recessive genetic disorder in Holstein cattle that affects lipid metabolism and causes young calves to die as a consequence of chronic diarrhea and failure to thrive.
The Melanocortin 1 Receptor (MC1R) gene (also called Extension) controls the production of black and red pigments in the coats of domestic cattle, creating base colors that may then be further modified by other genes.
The dun coloration in Dexter cattle is caused by the dilution of black pigment in the hair, producing shades of dark brown to gold. This color dilution is caused by a recessive mutation.
Bulldog dwarfism is a lethal genetic defect of Dexter cattle. Affected fetuses have severe disproportionate dwarfism, a short vertebral column, a large head, and are naturally aborted around seven months of gestation. The two known mutations are specific to Dexter cattle and may be present in Dexter crossbreds.
Pulmonary hypoplasia with anasarca (PHA) is a lethal genetic defect characterized by incomplete development of the lungs and severe subcutaneous fluid accumulation, leading to abortion or the birth of a dead calf.
A freemartin is a female that is born as a twin with a male and is sterile as a result of exposure to masculinizing hormones produced by the male in utero.
Paunch calf syndrome (PCS) is an inherited lethal defect of Romagnola cattle characterized by abnormal development of multiple organs, craniofacial deformities, an enlarged fluid-filled abdomen, and liver fibrosis. Affected calves are usually stillborn.
Polled cattle breeds have been selectively bred to lack horns. Polledness is a dominant trait: all offspring of a bull with 2 copies of a polled-associated mutation will be polled themselves.
Congenital pseudomyotonia (PMT) is a recessive genetic defect seen in Chianina and Romagnola cattle that impairs muscle function and is characterized by exercise-induced muscle cramping.
