Do Feeds and Supplements Go Bad? They sure do - but the labeling laws don't make it easy for you to figure out which ones may be out of date.  To be fair, a big part of the problem is determining when "out of date" (best not to feed) is likely to be. When we buy fresh dairy or meat products, canned or boxed foods, we expect to see "best by", "expiration" or "use by" dates. These are based on expected room, refrigerator or freezer temperatures. With horse feeds, there's no such thing as a standard room temperature. Feeds are stored under a huge range of temperatures and humidity depending on geographical location, time of the year and the facility itself. Another complicating factor is the composition of the feed and how it was manufactured. Properly dried whole plain grains and very dry ingredients like beet pulp retain their nutrition and have low risk of molding for about a year, but processed/broken grains, added fat or added molasses decrease the safe storage time to as short a period as 90 days.  High heat and humidity also lead to loss of vitamin potency. For best nutritional value and safety it is best to only use commercial feeds that are less than 3 months old. You will never find an expiration date on a feed bag, or even a clearly marked date of manufacture.  However, you will likely find a code on the tag or bottom of the bag that includes a Julian date format, or some variation of it, for date of manufacture.  Never assume a feed is fresh just because it's on a store shelf. When date of manufacture is straightforward it is likely to look like day-month-year, for example, 5Feb2018 would be February 5, 2018.  In the Julian system, month and date of the month are replaced by day of the year (first through 365th or 366 in a leap year). A manufacturer may use year-Julian day so 2018043 where year is 2018 and day of the year is 43.  Still others use a format that starts with a number or letter code of varying length to identify the mill where the feed was made, followed by a Julian date code.  This gets very complicated as you go through the decades of a century and have to figure in leap years.  https://landweb.modaps.eosdis.nasa.gov/browse/calendar.html.  Bottom line is, if your feed doesn't have an easy to read date on it, call the manufacturer to get details on their coding system. For the very freshest feed possible, look for a local mill that makes their own feed. These small mills have limited storage space, know their market and often make fresh feed every week.  Large barns that can quickly use up a minimum order of half ton to a ton of feed can often contract with the mill to have a custom formula of their choice made - usually for half what it would cost to buy the same feed from a large feed company. Supplements are even more of a mine field than feeds.  You will never see a clear manufacturing or expiration date. Even lot numbers are not required on the label but you may see one there or elsewhere stamped on the package.*  It may or may not be identified as a lot number. Before you buy a supplement, contact the manufacturer, ask where the lot number is located and if you can be told the manufacturing date if you call with the lot number. The longest shelf life is for inorganic minerals, e.g. oxides, sulfates, chlorides, phosphates, that have no flavorings or organic base such as alfalfa or flax seed. These will not support bacterial or fungal growth, keep potency virtually forever and the only issue may be clumping over time. Because they have an organic base, organic minerals do support organism growth and their shelf life is around 2 years. Liquid supplements of all types, including liquid fats, have the shortest shelf life unless preservatives are added. Supplements with a flax seed base may also go rancid in as short as 6 months depending on storage conditions. Horses can detect, and refuse to eat, levels of rancidity that are not obvious to us. Whenever possible, it is best to buy directly from a manufacturer rather than at the local level or even through a distributor. The more middle men are involved, the more likely the supplement may have had periods of improper storage conditions or have been in inventory too long. The manufacturer will have a vested interest is not selling old product - distributors often do not. If despite your best efforts you end up with a feed or supplement with obvious molding, an off or "old" odor, excessive crumbling, or one that your horse does not want to eat - take or send it back. Such a product is high risk of making your horse sick and has little chance of doing him any good. *Please note that Uckele formulas are stamped with a clearly indicated Best if Used By Date, as well as a lot number.