Study on the livestock diet is one of the main priorities in the management of rangeland in Iran. So, this study was conducted to compare preference values of plant species in three age classes of Kaboudeh sheep (one, three and five year old ones) in rangelands of Bavanat, Fars province, Iran. For each age class, four sheep were selected and their grazing times from different plant species were recorded using a timing method (chronometer) for two hours during the day. The effects of livestock age, plant species and their interactions on preference values of plant species were assessed using a factorial experiment (GLM test). Also, one way ANOVA was applied to compare preference values between plant species for each age class of animals. The results showed that the age of the animals and plant species had significant effects on preference values of plant species. Species of Poa pratensis and Avena fatua for young animals and Acer cinerascens for older animals had higher preference values. In addition, species of Poa pratensis and Prangos ferulaceae had appropriate preference values for all three age classes of animals. As vegetation cover in the study area is mostly consisted of the bushes and shrubs in autumn and on the other hand, sheep has little ability to graze this kind of plant species subsequently during the grazing period, they dominantly focus on herbal species. In general, animal diet demands cannot be provided from rangelands and it is required to use the methods of manual feeding with dry forage and supplements. One of the possible alternatives is to harvest and store the annual yield of P. ferulaceae in spring in order to feed the animals in autumn and winter. تفاصيل المقالة