Hi Cecil!
Why does poo turn white?
Thanks a lot,
Izbelle
Liver failure makes poo turn “chalky yellow-white.” If you have white poo see a doctor ASAP.
There’s also a good chance that the OP is talking about poo that has dried over a period of time. Like in the yard after sometime after the dog went poo.
poo.
poo. 
What Peter said.
You haven’t had an upper GI X-ray series lately, have you? The contrast agent can make your poopie pretty pale, too.
AHAHA yes, I was talking about poo that has been in the yard after a while, like when the dog goes poo poo 
. It just sort of came up in one of the wacky conversations I had with my goodfriend Chris, and we were both intrigued as to why poo turns white… after its been in the yard… after a while… And no, I havent had and X ray, nor do i have liver problems 
Bilirubin, urobilinogens, and several other pigments from the breakdown of hemoglobin are responsible for the usual color of feces and urine. These pigments are also light sensitive, and after a day or so in full sun, they will break down and lose their color. Thus, fresh dog poop will have it’s characteristic color for a few days, then turn whitish or light-colored from the loss of pigment.
Vlad/Igor
Hmm… That statement reminds me of photography somehow. 
Thanks Vlad!
My friend Chris also pointed out that not all petrified carrion turns white. Some turn really really black. Why does this happen? Does the existence of these pigments differ between species?
You got me on that one. What animal are we talking about? As far as hemoglobin metabolism goes among mammals, we’re all pretty close in terms of biochemistry. Offhand, I’d say that there’s another chemical present that turns dark when exposed to air or light, but I don’t know what it would be.
Vlad/Igor
No animal in particular, its just little things you notice and after that make you think, well after the initial ‘yeww’.
Bone meal.
After the more organic material decays/dissolves in the rain/etc, the more stable bone meal bleaches with exposure to air/sunlight.