The major gene of muscular hypertrophy in the Belgian Blue cattle breed.
A review. Data on experimental herds involving backcrossing studies of Belgian Blue and Friesian cattle and progeny test data on commercial herds showed that a major gene (mh), which is partially recessive, is responsible for the condition. Studies involving classical markers (coat colour genes and biochemical polymorphisms) revealed linkages with the mh gene. DNA fingerprinting showed a band cosegregating with the double-muscled condition in the progeny of a doubly heterozygous bull, indicating strong linkage. Anatomical and physiological comparisons showed differences between double-muscled and normal cattle, and performance data showed differences between the 2 groups of cattle in carcass traits, reproduction and milk yield.