ABSTRACT
Sheep share with other ruminants the ability to convert fibrous, often low-quality feedstuffs into valuable, life-sustaining products for human use, such as meat, milk, wool, and skins. Hair sheep have evolved under the influence of selection by both nature and man. Hair sheep are usually found at the lower altitudes in the tropics. Hair sheep also are found in southern India and southeastern Asia. Three types of fibers—wool, kemp, and hair—are found in the coats of sheep. Fibers are produced from primary and secondary skin follicles. Populations of hair sheep tend to be considerably more heterogeneous than are temperate-zone breeds. The heterogeneity within groups, whether attributable to relatively crossing or simply to lack of prior directional selection, offers an unusual opportunity for effective selection to improve productivity. This heterogeneity, coupled with the adaptation of the sheep to tropical environments through generations of natural selection, makes the hair sheep a genetic resource of great potential for tropical agriculture.
