You don't need a lab to judge a hay: with your eyes, your nose and your hands you can learn almost everything that matters. Here are the four things worth checking before giving it to an animal.
Color
A good hay usually has a muted green color, although a rain-fed hay can be paler or more yellowish without that taking anything away from its quality, as long as it keeps the whole plant intact. What is a bad sign is a hay that's faded or browned by rain, or has dark patches, which usually give away moisture or mold.
Smell
Your nose is one of the best judges. Healthy hay smells like dry grass, pleasant and clean. Any musty, damp or moldy smell is reason enough to rule it out: it means it's been stored badly and is no longer fit for consumption.
Texture
Picking it up by hand, a good hay has a mix of leaf and stem, not just tough stalks. The leaf is the part with the most nutrition and the one animals accept best; a hay that's almost all thick stem is less nutritious and gets used less well.
Dust
A quality hay gives off little dust when you move it. Too much dust irritates the airways, something especially delicate for horses, which are prone to respiratory allergies. If a cloud rises when you open the bale, that's a warning sign.
Hay is not straw
A yellowish but complete hay, with its leaves and seeds, shouldn't be confused with straw, which is just the plant's stalk once the grain has been separated and provides practically no nutrients. Real hay carries the whole plant; straw is for bedding, not for feed.
