Organ meats aren't as popular in the United States as they should be, says "New York Times" food writer Mark Bittman in his bestselling cookbook, "How to Cook Everything: Simple Recipes for Great Food." The distaste for cuts like liver probably stems from overcooking -- prepared medium-rare or medium, Bittman says, liver is tender and flavorful. Calf or beef liver is the most expensive, but, according to The Cook's Thesaurus website, lamb liver is a good alternative. The two are similar in nutrition, though some differences may make one a better choice for you and your family.
The U.S. Department of Agriculture reports that a 3-ounce, 81-gram serving of sauteed beef liver contains 3.8 grams of total fat, while the same serving size of cooked lamb liver contains more, at 10.7 grams of fat. Lamb liver also has more saturated fat -- 4.1 grams versus 1.2 grams in calf liver -- and approximately 100 more milligrams of cholesterol per serving.
Both lamb and calf liver are high in protein. A 3-ounce serving of lamb liver has 21.7 grams of protein; a 3-ounce serving of calf liver has 21.5 grams. For the average adult woman, this amount fulfills about 47 percent of her daily requirement of protein. For the average man, a serving of liver would supply 38 percent of his protein needs.
Meat like liver isn't a good source of carbohydrates. Neither lamb or calf liver contains any dietary fiber or simple sugars. Calf liver has only about 4 grams of carbohydrates in every 3 ounces, while lamb liver has 3.2 grams.
The U.S. Food and Drug Administration's guidelines for labeling nutrient content details that if a food provides 20 percent or more of a vitamin or mineral, it's considered an excellent source of that nutrient. By these guidelines, both calf and lamb liver are excellent sources of vitamins like vitamin A, vitamin B-12 and the B vitamins riboflavin, pantothenic acid, niacin and vitamin B-6. They are particularly rich in vitamin B-12. Adults need 2.4 micrograms of vitamin B-12 each day; lamb liver contains 73 micrograms in every 3-ounce serving, and calf liver has 67 micrograms.
Lamb and calf liver are excellent sources of iron, phosphorus, zinc, copper, fluoride and selenium, though they do provide different concentrations of the minerals. Lamb liver contains more iron, zinc, manganese and selenium, while beef liver is a better source of copper and fluoride.