To optimize breeding, only the mares in heat are shown to the stallions. The detection of oestrus (periods of heat) in mares on farms is conventionally carried out by the blower test. This test consists in having the mare sniffed by a whole horse (i.e. not castrated). It is then said that the horse blows the mare, hence its name blower. The use of a blower, also called booster or teaser, in stud allows both to check if the mares are in heat and to prepare them for the mating that will take place with other stallions.