This type hay is distinguished from sun-bleached hay in that all the hay will have the same yellowish color. Slight discolorations from sun bleaching, dew, or moderate fermentation are not as serious as the loss of green color from maturity, rain damage, or excessive fermentation or heating. There are two types of foreign matter, the non-injurious and injurious. Non-injurious means those materials in hay that are commonly wasted in feeding operations but, if eaten, are not harmful to livestock. These include non-toxic weeds, overripe grain hay, grain straw, corn stalks, stubble, chaff, sticks, and other objectionable matter.
Weeds are the most common non-injurious foreign matter found in hay.
They are usually not relished by the livestock and, when eaten, have little or no feed value. Hay containing weeds or other foreign matter is discriminated against on the hay markets. Injurious matter is material that is poisonous or will harm the animal when eaten. Don't buy hay containing injurious foreign material. Generally the smell of new mown hay is used as the standard for comparisons.