The plastic would hold heat and moisture...some folks store in plastic but I never do. I don't know about freezing.
If wanting to get alfalfa into the diet and not wanting to waste the pellets, one can either split this stuff with someone who feeds to horses, sheep, etc. or just use a hay net or something similar and hang some real alfalfa hay in the coop.
I used to put some alfalfa into my winter feed mix but found the birds will pick around it(to me, this means they don't want or need that much of that kind of greens) and the bulk of the stored feed would mold and go to waste. After that, I just made sure they had access to hay and they could sample as they wish. And they did.
If wanting to get alfalfa into the diet and not wanting to waste the pellets, one can either split this stuff with someone who feeds to horses, sheep, etc. or just use a hay net or something similar and hang some real alfalfa hay in the coop.
I used to put some alfalfa into my winter feed mix but found the birds will pick around it(to me, this means they don't want or need that much of that kind of greens) and the bulk of the stored feed would mold and go to waste. After that, I just made sure they had access to hay and they could sample as they wish. And they did.