I'm going to start taking my 3 1/2-4 week old ducks and geese outside in the daytime to let them forage and play around in the grass for a bit(just for short excursions with me right there with them!), and I was wondering how I should provide their grit. I bought MannaPro Crushed Granite for "all classes of poultry" tonight. How should I offer it to them? How much? For how long? Can I offer it and take them out the next day?