Some horse owners and most cattle producers use round bales as a source of forage, especially in the winter. As I drive around and see all of these round bales stored on the ground, I wonder if the hay owners realize how much hay they are losing by storing round bales in this manner. To answer this question, Brad Holmes at the University of Wisconsin performed a study looking at various methods of hay storage and calculated the loss with each method. Holmes is an agricultural engineer. He stored the hay using several different methods, including under a roof, plastic wrap or bale sleeve on the ground, covered hay using a rock pad, uncovered hay using a rock pad, uncovered on the ground using a net wrap, covered on the ground, and finally uncovered on the ground.
Certainly covering the hay under a roof was one of the best methods as losses of hay only approached 10%. However, wrapping the bales with plastic or a bale sleeve provided similar results. Covering the hay and placing it on a rock pad did have some increase in loss over hay stored under a roof, up to about 17%, but covering the hay was the main difference. Hay bales that were not covered but stored on a rock pad still had up to 46% loss of hay and now we are getting into losses that really make a difference. Surprisingly, uncovered hay on the ground with a net wrap only had losses of 25% while hay covered on the ground had losses up to 46%. The most losses occurred with uncovered hay on the ground, which had losses of over 60% of the hay. Even with a 50% loss, your hay is actually costing twice as much as you paid for it per bale and you could probably build a barn to store the hay with the amount of money lost in hay every year.