The speaker says it is necessary to talk about hay because

While talking about livestock, we’d have to say something about hay which is of vital importance for farm animals, especially the cattle.
    Hay is dried grass or other plants, cut as feed for farm animals. Many grasses are grown for hay in the world, among which alfalfa and white and red clover are very well known.
    Hay must be cut at a certain time to retain all the nourishment of the plant. When the grass goes to seed, the stem and leaves begin to rot. Therefore the hay should be cut when it is blooming so that all the valuable elements can be kept in the plant.
    When the hay is cut it should be spread on the field to be dried in the sun. Weather is very important in haymaking. A scorching sun will burn the nourishment out of it, and rain or dew will soak the salt and sugar out of it. Sometimes it is necessary to put straw layers in between the hay so that they will absorb moisture and keep it from fermenting, or turning sour. Of course, in some large farms, this is done by machines, which can save a lot of trouble. Hay is very essential to our way of living. If hay could not be stored and kept for the livestock to feed on, the cattle would die in winter and people would not be able to have enough meat to eat in the coming year.
    In some countries, haymaking has become a large industry. Hay is now pressed into bales, bound together in large bundles. These bundles are much easier for people to ship to far-off places where forage grasses do not grow naturally or where the livestock do not have enough hay to pass the winter.