The hayloft in which the animal fodder is stored should be as ventilated as possible. This precaution prevents the hay from being spoiled by stagnant air, especially when it has not been squeezed dry enough. Ideally, the barn must comprise at least two large ventilation openings and, when it is vast as in La Grange de la Haute Vallée, a sufficient number of skylights or windows. They allow drafts that would contribute to the right conservation of hay.