[Aaron]

Aaron asked the Naked Scientists:

Hi.

I was dog-sitting recently and i started thinking.  When i was a young kid i remember having to clean up dog poop in the yard and it was always a chalky white.  Nowadays, dog poop remains the same colour.

Obviously there was something in the dog food to do this, but, what was it? and why was it removed?

Love the show! I am curious if there is any possible way i'd be able to get a signed copy of Dr. Chris' The Naked Science book.  Unfortunately I live in the States, but I would be more than happy to pay all fees to ship across the sea.  

I am a big fan of science, and this podcast has quickly become my
favourite.

What do you think?