I get that. But it's not a reason not to give one's chickens some BOSS now and then, which was what I was suggesting. (I was not suggesting that the OP start making home made feed.)
If they are whole, they should be good for years (whatever the nominal expiry date on the bag). A seed is...
For the umpteenth time, I am not suggesting it as an exclusive feed, BOSS and nothing else. I am saying it can be fed as a component of a varied and diverse diet, rather than the homogenous ultra-processed synthetic-vitamin supplemented so-called 'complete feed' in pellet form.
black oil sunflower seed (aka BOSS) is fed by lots of people to their chickens (don't take my word for it, read around on it). Chickens are birds so bird seed is chicken feed (that shouldn't need checking, but hey, do so if you need to). They won't eat everything in your veg patch (don't take my...
And you think this why? How could you possibly know what seeds are in a random bag of bird seed? How many of the seeds in it have a nutritional profile posted anywhere? Old feed is almost certainly vitamin deficient.
No-one is suggesting it is a 'complete' feed. But it could be a very nutritious part of a varied diet - and the OP has said nothing about the age and laying status of the hens in question.
I find it odd that you want to deny your own chickens the good quality food you're apparently happy to buy for wild birds. Why?
Why don't you trust your eyes and the evidence your chickens provide for you?
Yep. It seems that, actually, you instinctively know the answers to your questions...