With 60 percent fat, the milk of the hooded seal has the highest fat content of any milk-producing animal. But you're not likely to find hooded seal milk on your grocery store shelves. Cow, sheep and goat milk are the most common supermarket finds, and they range between 3.5 percent and 7.5 percent milk fat.

Sheep Milk

Sheep's milk has the highest fat content of the three types of milk. Per 8-ounce glass, it has 17.2 grams of fat. Of this total fat, 11.3 grams are saturated fat, 4.2 grams are monounsaturated fat and less than a gram is polyunsaturated fat. A glass of sheep's milk also has 66 milligrams of cholesterol.

Goat Milk

Goat milk is next on the list, with 10.1g of fat per 8-ounce glass. Goat's milk has the same proportion of saturated and unsaturated fats as sheep's milk, with 6.5g of saturated fat, 2.7g of monounsaturated fat and less than a gram of polyunsaturated fat. A cup of goat's milk has only 27mg of cholesterol.

Cow Milk

About 90 percent of the milk consumed in the United States comes from cows, and it has the lowest fat content of the three commonly available milks. An 8-ounce glass of whole milk has 7.9g of fat. With a similar proportion of saturated and unsaturated fats, there are 4.6g of saturated fat, less than a gram of monounsaturated fat and a mere trace of polyunsaturated fat in a glass of cow's milk. You'll also get 24mg of cholesterol.

Because cow's milk has the largest size fat globules, it is easier to remove the cream from the milk to get low and nonfat varieties. An 8-ounce glass of reduced fat 2 percent milk has 4.8g of total fat.

Other Milks Around the World

If you happen to be traveling in other countries around the world, you might encounter different milks that Americans typically do not drink. One of those is buffalo milk, which has about twice the amount of fat as cow's milk, according to the Food and Agriculture Organization of the United Nations. Because of its fat content, buffalo milk is often used to make cheese.