A lot of farmers choose to store their own forage rather than outsourcing it from retailers due to economical reasons. However, making this decision means you make the sacrifice of potential feed spoilage as well. How do you minimize the amount of spoiled feed?
The Weather

The weather has a high influence as to the amount of damage received in your feed stocks. If your forage gets wet it will get damaged.
The Site
Landscape of cultivated ground Free Photo
The site you choose for storage impacts the amount of spoilage you get as well. Outdoor covered storage needs good site selection and preparation. Your site should have good drainage to try and minimize the amount of moisture present.
What Difference Will A Storage Shed Make?
Wheats spikes Free Photo
You are able to reduce feed spoilage by 50% depending on rainfall and the dryness of your storage site. Shed storage will allow you to preserve 66% at the least of your harvest.
The value difference in storing forage will depend on the volumes you produce.  The key point in achieving maximum saving is having flooring in your shed. Hay and Lucerne absorb water upwards from the ground.
Bale Size Etc
Hay Bales Agriculture Scenery Free Photo
The larger and denser your bales are, the lower the ratio is of surface to volume. However big bales need to be made from sufficiently dry material. Remember that if the moisture content is too high of your bales they will start rotting quickly.
Hay Shed Or A Cover?
Wheats spikes Free Photo
Of course a cover is cheaper than buying a hay shed, although the longer you are storing your feed and the higher volume you intend to store, the more practical a hay shed becomes. Also plastic covers tend to ‘sweat’ introducing moisture from above and limiting evaporation that could have helped to lessen the damage.