All cuts of beef are not created equal. They differ from each other in fat content and texture, as well as cooking times and methods. The arm roast tends to be tough and less flavorful than the rump roast. In fact, the magazine “Cooks Illustrated” describes the texture of an arm roast as chewy and grainy. For cuts of beef more tender and flavorful than the rump roast, try top sirloin steaks or a top round roast.
Part of the Cow
For butchering purposes, a cow has eight sections. The arm roast and the rump roast come from opposite ends of the cow. The arm roast comes from the chuck portion -- the shoulder -- which is the front-most part of the cow, directly behind the neck. The rump roast comes from the round -- the rear-most part of the cow -- including the butt and thigh.
The sinewy muscles of an arm roast need slow, moist cooking methods like stewing or braising to render them tender and juicy. Marinating an arm roast helps tenderize the meat and add flavor. Braise a 2-by-2-by-4-inch boneless arm roast for 1 ½ to 2 ½ hours and a 1-inch to 1 ½-inch rump roast for 2 to 3 hours. Use a dry-heat cooking method to cook the leaner and more tender rump roast, but braising and stewing also suit this cut of beef.
Calories, Protein, Cholesterol and Sodium
The same 3-ounce serving of arm roast or rump roast provides you with different amounts of calories, protein, cholesterol and sodium, according to the Texas Beef Council. The arm roast has 184 calories, 28 grams of protein, 86 milligrams of cholesterol and 56 milligrams of sodium. The rump roast has 178 calories, 27 grams of protein, 82 milligrams of cholesterol and 43 milligrams of sodium.
Vitamins and Minerals
A serving of arm roast provides you with 49 percent of your daily value, or DV, of zinc; 48 percent of your DV of vitamin B-12; 32 percent of your DV of selenium; 23 percent of your DV of phosphorus; 18 percent of your DV of iron, 16 percent of your DV of niacin, 15 percent of your DV of riboflavin and 14 percent of your DV of vitamin B-6. The same portion of rump roast contains 31 percent of your DV of zinc; 35 percent of your DV of vitamin B-12; 34 percent of your DV of selenium; 23 percent of your DV of phosphorus; 16 percent of your DV of iron, 17 percent of your DV of niacin, 13 percent of your DV of riboflavin and 15 percent of your DV of vitamin B-6.