Hey hay. Hay is more complex than you might think! Hay is used as food for different types of livestock during times when there’s little fresh grass. Hay mostly consists of grass, but the age of the grass when it is harvested, determines the quality of the hay. Harvesting hay at the right moment is already difficult enough, but keeping it stored correctly is even more complicated. Hay that's too wet may lead to mould or even spontaneous combustion. Dead creatures that get into the hay during the harvesting period can also produce substances that are toxic when ingested by livestock (like botox).