Hay looses its nutritional value with time. Three year old timothy is about as good as straw out of the field and should be supplemented with a grain for livestock.
The nutrients that are added to the pellets have a half-life of about six months. My chins start feeder dumping when a feed hits four months here. Sometimes I forget to check the mill dates and it happens more quickly than I'd like.
Most of the show rabbit feeds do contain oil and it smells pretty nasty when it goes rancid.
What about the processes you can't see? Calcium for bone density, amino acids for cellular reconstruction...
As breeders we have to consider this. As a pet it may just mean your chin has a greater chance to break a leg or not heal as well after surgery. For a breeder it can mean everything from weak/dead babies to weak/dying moms, a rash of malocclusions in younger animals, a herd-wide outbreak of a disease/infection that is not normal.... all from poor feeding practices.
To answer the OP's question, an adult chin consumes about a pound of feed a week here.
) You should be able to use up the feed within six months.
