Of natural causes.....

.... and low fat cows. How hilarious.

Scientists discovered a cow, later named Marge by researchers, carrying the mutant gene in a dairy herd they were testing in 2001, Vialactia chief scientist Russell Snell said.

Vialactia, a subsidiary of the Fonterra Cooperative Group, one of the world's largest milk companies, bought the cow for 300 New Zealand dollars ($218) and moved it to a research site.

While she looked like any other Friesian cow, testing revealed that Marge's milk contained about 1 percent fat, compared with about 3.5 percent for whole milk.

Offspring from the cow also produce low-fat milk, showing the genetic trait is dominant, Snell said.

I like the Friesians - all black and white and kinda cute. And now they're low fat too? I wonder what Marge has been eating!