Unopened feed - storage length inside

I searched quite a bit but didn't find anything about storing feed inside...

Back in October my 3 week old meaties (30 of them) got eaten by coyotes. A couple days before I bought 2 bags of Dumor starter/grower feed (first time not buying Purina so this adds an element of unknown too). I put the feed in the basement for the winter as I'm hoping to save it until March/April when I get my next batch of meaties.

I understand that if I open it up in spring and it's clumpy, moldy, etc to throw it away. But let's say I open it and it seems fine...is there any degradation to the nutrients, vitamins, etc that would hinder the growth and health of the new chicks?

I feel like I should be safe and just toss it (is there something else it's good for?) and eat the $30 or so...