I never use my slow-cooker for poultry, only for beef and pork. I have often made both pulled pork (after smoking in the Webber kettle with chunks of apple wood) and shredded beef, as well as stew and soups with excellent results, even when cooking for 10 to 12 hours or more.
To be successful with meats, one only needs to understand what meat does at different temperatures. At 140 F. or so, it begins to turn gray and the nasty microbles begin to feel the heat. By 145, the microbial pests are dying, but the meat is still tender and juicy. By 165, poultry is completely safe and is white throughout, but still juicy and tender. Between 170 and 175, the muscle fibers begin to tighten, making the meat tougher and squeezing out the moisture. But 180, you're eating cardboard.
Where the heat comes from doesn't matter, be it from hot liquid, a dry oven, contact with a hot surface, or by radiation , either thermal (charcoal/gas-grill/broiler/wood-fire), or elctro-magnetic (microwaves). The meat reacts to the temperature, not the heat source.
My slow cooker has three temperature settings, high, low, and warm. I use high to quickly bring the vessel to temperature, then turn to low until the meat is done to my liking (three to four hours depending on what I'm making), and then on warm, which is designed to keep the food at around 140 to 145 degrees or so. I never let the liquid come to a boil. But I also always remember that there is a place where the meat doesn't follow the rules as stated above.
As meat with significant connecting tissue and fat comes to around 180 degrees, that connecting tissue and fat begins to melt and dissolve into the liquid. I lubricates the individual meat strands, allowing them to slide apart easily (pulled pork and shredded beef, or a wel-done pot roast). The meat will literally fall apart if disturbed, say by lifting it to a platter. So, the best roasts to use for pot roast, and shredded or pulled meat dishes should be lower quality pieces with significant connecting tissue, like a chuck roast, blade roast, brisket, etc. With pork, the roast and other cuts from the shoulder should be used.
Lean mets such as tenderloin, sirloin, round, hams etc., easily dry out and become tough when cooked above 160-165 degrees. So think about what you are trying to make, and choose the right cut of meat for the job.
Oh, one more thing, sausage dry out and become tough when boiled. To add flavor to roasts and sausages, brown in a heavy pan and then add to the slow cooker. Cook on low heat until sufficently done and use the warm setting to hold at the correct temperature until served.
If you understand the nature, the physics of cooking, then you will find yourself a very successful cook indeed.
Seeeeeeya; Goodweed of the North
(just kidding)
