This MASSIVE animal is not your average cow. This is a Belgian Blue, a behemoth bovine of muscle and sinew. This cow looks like they've been hitting the gym hard and every day was a full body workout. Belgian Blues aren't actually pumping iron, of course. Breeders have selectively bred them for over two centuries to come up with this enormously buff cow. They even go as far as shaving the cows in specific areas to accentuate their musculature
The Belgian Blue's ability to produce huge, lean muscles was first noticed in 1808 by a man named George Culley. The modern Blue as we know it was not developed until the 1950's by Professor Hanset. In 1978, the breed was first introduced to the United States. The Belgian Blue has a natural mutation in its myostatin gene, a protein that inhibits muscle growth. The mutation essentially takes the "cap" off of how much muscle they're able to grow.
H/T: Darrel Floyd