How long should you cook a 5 lb meatloaf at 300 degrees?

You should not cook a 5 lb meatloaf at 300 degrees. The USDA recommends cooking ground beef to at least 160 degrees Fahrenheit to kill harmful bacteria. To be safe, cook a 5 lb meatloaf at a temperature of at least 325 degrees Fahrenheit until it reaches an internal temperature of 160 degrees Fahrenheit. Cooking a 5 lb meatloaf at 300 degrees could lead to foodborne illness.