I wouldn't give it fresh, and if you do you should introduce it very very slowly. Do not give them to much. Work up to it being an occasional treat. Keep a close eye on poo quality. A little moistness or slightly mushy textures on the poo are to be expected anything beyond that back off and offer burnt toast. Also if you offer it fresh you may want to offer acidiphilus(sp??). This will help make sure the GI tract stays healthy, doesn't get to stressed and does not result in bloat. The best thing to do would be to offer it as a cured hay instead though. Also it is very important to make sure it is pesticide free so your fur balls don't get poisoned. If you offer it as a hay what ever you do DO NOT WASH IT! It will grow mold and possibly kill your chinchillas. Rye Grass hay would be fine offered often and not just as a treat. Rye grain however should only be offered very very sparingly if at all. Hope this helps.