Zinc oxide is the metal zinc that has been oxidized. The chemical formula is ZnO, 1 zinc atom and 1 oxygen atom held together by an ionic bond. Zinc oxide does occur in nature as the mineral zincite, but it is quite rare and commercially unavailable.
I have done a few stool samples in my time and have always just stored them in the fridge, until the next day to take them into the docs. Good luck hun I hope they get it sorted.
(although I don't know if I'd let these guys clean out my fridge.)     So if you take an average of all of this information, I'd say you can most safely keep pickles for 12-18 months. Anything beyond 18 months and I'd take a good, long look at them before eating.