"Meet the Supercow"

Via a link at Bits & Pieces, a National Geographic short about cattle that have been selectively bred to avoid the gene (myostatin) that limits muscle growth:

See also Cow Engineered to Produce Less Allergenic Milk; an article on cows supposedly genetically modified to produce human breast milk (I think the key word there is "supposedly"); an article on blocking myostatin in macaque monkeys to increase muscle growth; and an article about super strong children lacking the gene for myostatin.