Abstract
The study on the livestock dietary and preference value of different species are essential for
rangeland management. Therefore, this study was carried out to evaluate the preference indices
of 14 plant species in Kahnuj, during two different phenological stages (vegetative growth and
after-seed-dispersal). The close observation method was used to measure the preference index
for three age classes of Rainian goat (one, three and five years). The results showed that main
and interaction effects of goat age, plant phenological stage and the kind of plant species on
preference values were significant. Older goat consumed a higher time to graze in the study
area. Stipa capensis had the highest preference index and Rhazya stricta had the lowest. The
preference index of most plant species was significantly variable between two phenological
stages. In addition, in each phenological stage, the preference value of plant species was
significantly different. In the vegetative growth stage that annual plant species were abundant,
goats mostly focused on these plant species for grazing. However, in the after-seed-dispersal
stage in which the annual cover decreased, goats (particularly older ones) focused on shrubs for
browsing. As a result, Rainian goat is a grazer in the normal situation and he can be a browser
in the hard condition. It was suggested that the cover of Taverniera cuneifolia to be increased in
the study area in order to compensate the deficiency of forage in long term. Artificial foraging
is useful to reserve the performance of goats (particularly younger ones) in short term.
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