Here's a pretty well-documented summary from Eat Wild (http://www.eatwild.com/healthbenefits.htm):
Summary of Important Health Benefits of Grassfed Meats, Eggs and Dairy
Lower in Fat and Calories. There are a number of nutritional differences between the meat of pasture-raised and feedlot-raised animals. To begin with, meat from grass-fed cattle, sheep, and bison is lower in total fat. If the meat is very lean, it can have one third as much fat as a similar cut from a grain-fed animal. In fact, as you can see by the graph below, grass-fed beef can have the same amount of fat as skinless chicken breast, wild deer, or elk.[1] Research shows that lean beef actually lowers your "bad" LDL cholesterol levels.[2]
Because meat from grass-fed animals is lower in fat than meat from grain-fed animals, it is also lower in calories. (Fat has 9 calories per gram, compared with only 4 calories for protein and carbohydrates. The greater the fat content, the greater the number of calories.) As an example, a 6-ounce steak from a grass-finished steer can have 100 fewer calories than a 6-ounce steak from a grain-fed steer.
(For more information about Missouri Beef as Best Health Food, see below pdf...)
