chemical composition and in vitro digestibility of some range species in rangelands of chaharmahal and bakhtiari province, iran

five common range forage including agropyron intermedium, bromustomentellus, hordeum bulbosum, cousinia bakhtiarica and scariolla orientalis, weresampled during three phenological stages, from controlled rangeland stations over fivelocations in chaharmahal and bakhtiari province, iran. all samples were chemicallyanalyzed for crude protein (cp%), in vitro dry matter digestibility (dmd), organicmater digestibility (omd), ether extract (ee), crude fiber (cf), total ash, neutraldetergent fiber (ndf) and acid dtergent fiber (adf). results for crude protein (cp%)showed significant differences between phenological stages in all of species. maximum cp(15.2%) was found in vegetation stage of hordeum bulbosum and the minimum (2.9%)was in seed ripening stage. the cf% was significantly different between phenologicalstages as well as the species. the minimum and maximum values of cf% were found inagropyron intermedium in coosinia bakhtiarica, respectively. similarly, the minimumvalues of ndf and adf were found in vegetative stage of scariolla orientalis andagropyron intermedium respectively, but the maximum values were obtained in seedripening stage of hordeum bulbosum and cousinia bakhtiarica. the dmd and omd%showed slightly reduction passing from vegetation to seed ripening stage in most of thespecies. the highest dmd and omd% had been observed in vegetation stage of scariollaorientalis and the lowest were in bromus tomentellus. it can be concluded that in the earlystage of growth, the quality of forage in range species is adequate for livestockproduction but during that stage, the greatest problem is its lower quantity. by progress ofthe vegetation stage toward the seed ripening stage, the nutritive value of all speciesdecreased thus grazing animals oppose to nutrient deficiencies.