Over 300 million turkeys are killed every year in the United States, 40 million of them specifically for Thanksgiving. The majority of these are raised in factory farms where they are stacked in cages in windowless sheds where they can't live naturally (or happily) in any sense of the word. Often they cannot move, and many die in the conditions before they are fully grown. They are debeaked and declawed without anesthesia, making it difficult or even impossible for them to eat, and research shows that they feel the pain of this for the rest of their lives. Those who survive are fed until they are grotesquely obese and cannot stand because their skeletons are too weak from confinement. Over-burdened in this way, and trapped in close quarters with too little oxygen, many turkeys die when their hearts explode from the physical stress.
The birds are unable to reproduce naturally in these conditions, and the males are "milked" for their semen, which is then shot into the females with a syringe or tube. Turkeys do not recieve even the scant protection given to pigs and cows by the Humane Slaughter Act and many are tied upside down still alive and conveyed to the part of the factory where they are knifed. Not all die right away and suffer unspeakably by bleeding slowly to death.