Have researched this topic both for human as well as animal food - and
the bottom line is that there are no safety issues by using something
past it's stated "best by" date.

The issue gets trickier with the "use by" date. That begins to cover
things like how was something stored and if it was subject to
temperature or light extremes (think MILK!).

Almost always fresh milk is still good past well past it's "use by"
date if you haven't left it sitting on the counter in an 75 degree
kitchen for two hours three or four times. ;)  Fortunately, milk is
always subject to the "sniff" or "taste" test. You won't die if it's
sour, but you won't be happy drinking it either!

As for best by - there is a bit of the same issue. How have you kept
the food? If "bagged" like potato chips or pet food, did you leave
it in a moist basement where it could be potentially compromised by
moisture? Is the bag all paper, or a sealed jug or poly bagged?

Fresh spinach with a use by date two weeks ahead, versus a dry dog food
with a use by date 18 months into the future are two totally different
issues. If you properly refrigerated the spinach and didn't leave it
sitting about on the counter to get yuucky, you could probably get a
week to 10 days more life from it (I am not talking about nutritional
value - that begins to deteriorate from day 1 when it is picked).

So for something like dry pet food (or human cereal, crackers, flour,
sugar, etc), then the longer it had a shelf life to begin with then
the longer you have beyond that stated use by date you have.

Again, the taste may be a tiny bit compromised, but not enough to
concern yourself unless you are using it 2 years later! :)

So bottom line - for 6 months to a year for dry pet food, I'd not worry
in the slightest unless you kept it in a wet basement.

Ann Gruden
Ferret Assn of CT

[Posted in FML 7372]