Unopened in it’s air-tight package, Chaffhaye will remain preserved and fresh for at least 16 months. The nutritional value of Chaffhaye does not decrease with time. We have tested 5 year old bags of Chaffhaye that are no different nutritionally to a recent bag. Once opened, Chaffhaye acts like any fresh product. By opening the bag, the forage becomes exposed to oxygen and begins to lose its freshness. As a guide, Chaffhaye will remain fresh 7 to 14 days after opening, depending on weather conditions. For this reason, an opened bag should be stored out of the sun with the top rolled down and fastened to prolong freshness. If for some reason Chaffhaye does spoil you and your horse will certainly know. It will have a very bad, rotten smell.