The below text is taken from the official Turkey Slaughter training manual (PDF) used by a Food Inspector-to-be for the United States Depeartment of Agriculture's Food Safety and Inspection Service. Now I intend to eat turkey like the average American, but this was just too good to pass up.
Turkey Plant Operations
Turkeys are hauled to the plant on truck beds or trailers in crates, fixed coops, or batteries.
When the turkeys are readied and unloaded for slaughter, the veterinarian (or a food inspector under his/her supervision) performs antemortem inspection by observing the turkeys on a lot basis.
The turkeys are hung by the shanks in shackles hooked to an overhead moving chain that conveys the live turkeys toward the stunning area prior to the neck cutting and bleeding areas.
Scalding of the bled turkeys occurs when the shackles pass through an immersion scalder filled with heated water, which is agitated by recirculation pumps.
In place of an immersion scalder, some turkey slaughter plants shower carcasses with hot water and then convey them through humidity cabinets where they are sprayed with steam. This system avoids the community bath of the immersion scalder.
Picking is done mechanically; usually there are several pickers used and each concentrates on a different area of the turkey to insure complete feather removal.
The shackled dressed turkeys sometimes are singed by a gas flame following picking, This burns the fine hair or feathers off the skin. The carcasses then pass through a wash cabinet, which is equipped with sprayers.
The hock joints are severed and the shanks are removed from the carcass prior to transfer of the carcasses to the evisceration line. The carcasses may be hung by the hocks or by the necks to make the subsequent removal of the crop and trachea (windpipe) easier.
The neck and both hocks of each carcass are placed in the shackle. This three-point suspension of the carcass facilitates the evisceration process.
Before the viscera can be removed, some cuts have to be made into the carcass. The vent area is cut free by a circular incision. Next, if a modified J-cut is used, a cut is made to the point of the keel. If a bar-cut is used, a transverse cut is made caudal to the point of the keel. Either method is approved for use provided the requirements of uniform presentation are accomplished in a sanitary manner.
Drawing, or viscera removal, is accomplished by pulling the viscera free from the body cavity and placing it consistently either to the right or left of the tail. Generally the esophagus will be the only natural body attachment remaining inside the body cavity.
The USDA food inspector inspects the eviscerated carcasses for wholesomeness. The viscera and the outside and inside of the carcass are manipulated in a manner that insures that only wholesome product is passed. Unwholesome carcasses and parts are condemned for human consumption and are positively controlled until proper disposal is completed.
Removal of the heart and liver from the viscera is part of the giblet harvest and trimming, which occurs next. The heart cap is removed from the heart, and the gall bladder is removed from the liver. Next the liver and heart are sent to an ice-and-water chiller.
The removal of the gizzard finishes the giblet harvest from the viscera.
The gizzard is removed by cutting anterior and posterior to its attachment to the gastrointestinal tract.
The gizzards are placed in a machine which splits (peels) and cleans their surfaces. The surfaces are then flushed, and the gizzards are chilled in ice and water.
After the viscera is removed, the lungs can be vacuumed from the chest cavity.
The crop and trachea are pulled free from the slit in the neck. If the oil sacs have not already been removed, they are cut off the tail.
The heads are removed and a final check of the carcasses is made to ensure all eviscerating processes have been properly completed. Then the carcasses pass through a final wash.
After the wash, the neck bones are cut. The necks may be placed inside the body cavity or chilled separately from the carcasses in vats of slush ice.
Next, the tails are cut, and, if they are used by the plant, hock lock wires are inserted in those carcasses that will be trussed. Tucking and trussing the legs of the carcasses is usually done prior to chilling.
Ice-and-water chillers are used to lower the product temperature. Carcasses and giblets are chilled separately.
After the initial chilling, the carcasses are hung on a drip line and drained.
Grading, if requested, is done next. Grading is a voluntary service performed at an additional expense to the plant.
Some carcasses are sent to the cut-up line. Carcass parts are packed in tray packs with plastic overlay, boxed, or bagged.
The giblets are wrapped and stuffed into the whole carcasses.
At the bagging station, the carcass is placed in a plastic bag.
The air is vacuumed out of the bagged carcass and the bag is closed with a clip. The bagged carcass then passes through a shrink tunnel, where it is sprayed with hot water. This procedure shrinks the plastic bag to conform to the shape of the carcass and results in an appealing consumer package.
The whole bagged carcasses and containers of cut-up parts are weighed to confirm, adjust, or mark the net weigh of the product. In some plants the price per pound and the total price of the product may be applied to the outside of the product package.
An immersion freezer is used by some plants to put a crust or quick chill on the product. This process helps prevent freezer burn on the carcass surfaces. Most immersion freezers contain solutions of propylene glycol or brine. As the bagged carcasses exit an immersion freezer, they must be sprayed with water in order to remove any freezing solution from the package.
The product is sorted and packed prior to entry in to the blast freezer.
Usually the air blast or plate-type freezer is used to freeze the product solid.
It is not usual for turkey plants to thaw frozen carcasses and cut-up or further process them some time after slaughter.
Once frozen, the product is ready to be shipped to food markets.