Belgian BlueFrom Wikipedia:
Belgian Blue cattle are a heavily-bred breed, producing extraordinary amounts of meat. The sculpted, heavily muscled appearance is known as "doubled muscled", and is a trait shared by the Piedmontese breed. Critics call Belgian blues "monster cows" and some countries have advocated eliminating the strain [1]. They are often unable to give birth without caesarean section.
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. This mutation also interferes with fat deposition, resulting in very lean meat.
One human boy in Germany was born with the same mutation. The gene is referred to as "Mighty Mouse" and the boy has been called "superboy" by the press.
