Published online by Cambridge University Press: 22 September 2009
Forages are usually associated with grasslands, but they also occur and are used widely on roadsides, in fallow areas, and as crop residues. In temperate areas livestock is grazed on domesticated forages. In the tropics livestock use native grasslands (Africa, Australia), naturalized grasslands (tropical America, Asia), or grasslands improved with selected wild species (tropical America). The worldwide exchange of forage germplasm has involved relatively few accessions of some widely adapted species, and the need exists to increase the diversity of these cultivated forages.
BOTANY AND DISTRIBUTION
Forages comprise different species, mostly from the Gramineae and Leguminosae families. Forages that have been domesticated and cultivated since historical times include lucerne (Medicago saliva L.), berseem (Trifolium alexandrinum L.) and red clover (Trifolium pratense L.) (Mannetje et al. 1980). Others have been cultivated more recently, such as white clover (Trifolium repens L.) and subterranean clover (Trifolium subterraneum L. sensu lato), ryegrasses (Lolium), Festuca and Phalaris. Wild species have been distributed and used widely: 40 million ha of Brachiaria decumbens Stapf in South America (Miles et al. 1996) and about 1 million ha of Stylosanthes species in Australia.
A great number of families, genera and species can be considered as forage and it is not practical to give botanical details of every species, including synonyms. Vernacular names of forage species have been documented (Mejía 1984; Skerman et al. 1988; Skerman and Riveros 1989; Wiersema et al. 1990; Mannetje and Jones 1992; Barnes et al. 1995; Brako et al. 1995).