For tender meat, use the thick, bone-in variety, and cook in the slow cooker on low for 5 to 6 hours. Thinner cuts may only take 1 1/2 to 2 hours. The center should be 140ºF to 145ºF as measured with a food thermometer before removing meat from the heat source, with a three-minute rest time before slicing and enjoying. (See temperature & resting tip above)