"Best By" generally imparts that the product will retain its best flavor, color or consistency up through that particular date - but it is safe to eat until after that date. "Use by" is generally seen on packages of fresh foods like Milk or meats, and really should be used by that particular date, or frozen by that date if you need to keep it around longer. Fresh foods all have bacteria within them and by the time the use by date has rolled around, the fresh foods are no longer "fresh" but instead are heavily laden with active bacteria and the bacteria are turning the foods into being unsafe for HUMAN consumption. "Expires by" depends upon the product. Medicines and even toothpaste and deodorant have expiration dates. Most medicines can be used past their expiration date - but have lost some efficacy. I tend to buy toothpaste when its on special 2 for one tubes and being a single adult house hold (without kids to smear the walls with the toothpaste) these two tubes last a VERY VERY long time. Much to the consternation of some folks - I am still here although I keep using expired toothpaste and yes, even expired deodorants! "Sell by" dates are self explanatory and geared of course to retailers to rotate their stock. When it comes to pet foods - there aren't that many regulations (which is why the FDA wants the AAFCO to take over and establish some). Most kibbles are designed with about a year shelf life. But some of the "higher end" kibbles use a much shorter shelf life. This is usually tied to the fat content and moisture content of the kibble. Fats WILL go rancid, especially when stored improperly. Higher moisture contents allow faster bacteria activity. There are all manner of ways to increase the "life" of foods - BHA, BHT are chemical additives that offer longer shelf life but have been linked to health problems, Citric Acid helps retain flavor retards discoloration and waylays some bacteria activity. Freezing puts bacterial activity in suspension but the freezing alters the cell walls of the food so when thawed the bacteria have an easier job to invade. Which means you need to use the food quickly after thawing. What may have kept a week to ten days refrigerated fresh, may only last a few days after thawing before bacteria turn it. Pasteurization puts foods at a very high temperature for specific time lengths, in effect flash cooking the bacteria currently present on or in the food. Freeze drying removes the moisture from food at the same time freezing the remaining fibers rendering a product with VERY long shelf life that to be used can either be eaten as is or reconstituted with water to be cooked. Flavor is somewhat diminished though and textures get rather interesting after reconstitution. Air drying (dehydrating) removes the food's moisture by long slow low heat or forced air method and also renders a product with a very long shelf life. Most people are familiar with jerky - which is usually seasoned to taste prior to drying. While jerky does last a very long time ( much longer than fresh meat) it too will eventually succumb to bacteria and molds. All this natural decay of fresh food is one reason kibble was invented. Interestingly there is a definite trend for kibble manufacturers to become more "natural" and supposedly add "real meat sources" or "bits" - so shelf life of kibble is shortening and kibbles will turn. Kibble can also suffer from infestations of mites, moths, meal worms, meal bugs, ants, roaches and other pests.This in addition to molds, fungi, salmonella, and other bacteria. Problem is kibble already starts out with a yucky smell so with odor being one of the quickest ways to notice if a food has turned - you could feed turned kibble without realizing its gone bad. Your pet may not eat the turned kibble right away, but will eventually when hunger demands. Now you've ended up serving who knows what that went IN to the kibble topped off with who knows what invading the kibble and poor snug 'ems has to eat the junk! Ewwww! If you are feeding just a few pets it isn't necessary to buy a 40 lb bag of kibble unless you can store that in a freezer. I'd recommend storing kibble in a freezer any way. Air tight containers may sound nice, but every time you open it air gets in - right? Also I have yet to see a vacuum packed kibble bag - so putting it in an air tight container at home isn't going to do much to preserve what was in the bag already. Mix together what you'll feed in a week. Store the remainder in the freezer. Put your week's mix in a container and keep it in the fridge. Personally I say end the confusion and simply feed raw/ natural/ whole prey - the USE by date is clearly marked on that package of fresh meat - or you may even know when the food animal was slaughtered. No chemicals, no issues with storage, supreme digestibility, safe, superb oral health and easy clean up from the ferret's other end! Cheers, Kim For ferret help and info: http://holisticferret.proboards60.com/index.cgi http://ferretopia.proboards51.com/index.cgi yahoo groups Natural Ferrets [Posted in FML 7376]