I've been trying to find a source or explanation for this information ... but no luck so far. Do you happen to have a link to a site that details the "resting" times for turkeys and chickens? And maybe a scientific explanation about why resting is necessary?
We raised our first turkeys this year (massive Broad Breasted Bronze). Some of our customers had bought live turkeys before and insisted that they wanted theirs processed the day before Thanksgiving, so I presume these birds rested only a few hours before they were cooked. Everyone is saying how amazingly delicious they were -- flavorful and moist and they all cooked way faster than expected considering their enormousness. We ended up having to process one way early in November so we kept that for ourselves. It did spend some time in the freezer and it was also quite delicious. I should say "is" delicious ... we'll be eating from it for quite a while.
The resting is needed because rigor mortis sets in after death. There is a chemical change which takes place causing the muscles to stiffen (staring from the head downwards through the body) until the body becomes "stiff as a board". Allowing the bird to rest for a few days allows the muscles to relax. I check the leg/thigh/hip joints to see how easily the leg will bend. If it bends easy then I know rigor has passed.
I did a google search for you for the scientific explanation.. and i came across this website:
http://chemistry.about.com/cs/biochemistry/a/aa061903a.htm
(for those who do not like to click links here's what they had to say on the subject):
"A few hours after a person or animal dies, the joints of the body stiffen and become locked in place. This stiffening is called
rigor mortis. Depending on temperature and other conditions, rigor mortis lasts approximately 72 hours. The phenomenon is caused by the skeletal muscles partially contracting. The muscles are unable to relax, so the joints become fixed in place.
More specifically, what happens is that the membranes of muscle cells become more permeable to calcium ions. Living muscle cells expend energy to transport calcium ions to the outside of the cells. The calcium ions that flow into the muscle cells promote the cross-bridge attachment between actin and myosin, two types of fibers that work together in muscle contraction. The muscle fibers ratchet shorter and shorter until they are fully contracted or as long as the neurotransmitter acetylcholine and the energy molecule adenosine triphosphate (ATP) are present. However, muscles need ATP in order to release from a contracted state (it is used to pump the calcium out of the cells so the fibers can unlatch from each other). ATP reserves are quickly exhausted from the muscle contraction and other cellular processes. This means that the actin and myosin fibers will remain linked until the muscles themselves start to decompose."
Then they go on to add: "Rigor mortis can be used to help estimate time of death. The onset of rigor mortis may range from 10 minutes to several hours, depending on factors including temperature (rapid cooling of a body can inhibit rigor mortis, but it occurs upon thawing). Maximum stiffness is reached around 12-24 hours post mortem. Facial muscles are affected first, with the rigor then spreading to other parts of the body. The joints are stiff for 1-3 days, but after this time general tissue decay and leaking of lysosomal intracellular digestive enzymes will cause the muscles to relax. It is interesting to note that meat is generally considered to be more tender if it is eaten after rigor mortis has passed."
I hope this helps