With some of the legume hays, the estrogen content can be important. If you are having breeding problems, consult with the extension service or local Agricultural Ministry, or school. If you use alfalfa on a regular basis, you might want to consider supplementing the diet with a calcium rich food, such as calf manna. All feed should be used within 90 days as a good rule of thumb. It is impractable to order more than you can use in 3 months, and you can store all but the weeks' worth in the freezer.
Food is food.
Pellets, oats, and hay can be kept in the freezer. Just use common sense, keep in closed containers, and don't let it get damp when defrosting before use. They all deal in hay on a regular basis. Remember, healthy food is a healthy animal.