steve2: Cold Steel, "autologous" blood transfusions (i.e., using one's own blood) are forbidden on the grounds that once blood leaves the body it is not to be stored but dispensed with.
Yeah, but if that blood comes from a cow, it's okay to store it and use it later.
Cow's blood is fine. Drain blood from a cow (a dead cow), store it, chill it, process it...and that is okay to pump into your veins.
And so is expired human blood.
But, the WTS/Org says "no" to storing your own blood and using it.
Unless you are a cow.