If a food is not edible for human beings but is suitable for animal consumption, does it have the status of Muktzeh on Shabbat?
The Halacha regarding such food depends on whether animals for which this food is edible are prevalent in the given society. Today, many people own dogs and cats as pets, and therefore food suitable for consumption by these animals would not be considered Muktzeh, even for a person who does not own a dog or cat. Thus, chicken bones left on one's plate, which are suitable as food for dogs, may be moved on Shabbat even by those who do not own a dog. Since dogs are prevalent, and the bones could be fed to a dog, one may move them on Shabbat. If a person has food that is suitable for consumption only by an animal that people in society generally do not own, he may not move it on Shabbat unless he happens to own that animal.
Remnants of food that are inedible for all animals, such as pistachio shells and olive pits (assuming no fruit of the olive is still attached to the pit), are of course considered Muktzeh on Shabbat and may not be moved.