Belgian Blue

Belgian Blue cattle are a beef breed from Belgium, known in French as Race de la Moyenne et Haute Belgique. Alternative names include Belgian Blue-White, Belgian White and Blue Pied, Belgian White Blue, Blue and Blue Belgian. The sculpted, heavily muscled appearance is known as "double muscling", and is a trait shared by the Piedmontese breed. They are named for their typically blue-grey mottled hair colour, although it can vary from white to black.

The Belgian Blue has a natural mutation of the gene that codes for myostatin, a protein that counteracts muscle growth. The truncated myostatin is unable to function in this capacity, resulting in accelerated lean muscle growth, due primarily to hyperplasia rather than hypertrophy. The defect in the breed's myostatin gene is maintained through linebreeding. This mutation also interferes with fat deposition, resulting in very lean meat. The neonatal calf is so large that Caesarean sections are routinely done. Double-muscled cows also can experience dystocia, even when bred to normal beef bulls or dairy bulls, because of narrowing of the birth canal.

The breed originated in central and upper Belgium in the nineteenth century, from crossing local cattle with Shorthorn cattle from the United Kingdom and probably with Charolais cattle. At first there were milking strains and beef strains of the breed. The modern beef breed was developed in the 1950s by Professor Hanset, working at an artificial insemination centre in Liege province.

Critics call Belgian blues "monster cows" and some countries' governments, including Denmark, have advocated eliminating the strain.