Seasonal Changes of Nutritive Values and Digestibility of Range Forage of Chaharmahal and Bakhtiari Province, Iran

Range forage of Vicia variabilis, Astragalus spp., Medicago sativa, Prangos uloptera and Sanguisorba minor was sampled during three phenological stages from the controlled rangeland stations in Chaharmahal and Bakhtiari province, Iran. Samples were analyzed for the determination of Crude Protein (CP%), Ether Extract (EE), Crude Fiber (CF), total Ash, Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF), in vitro Dry Matter Digestibility (DMD) and Organic Mater Digestibility (OMD). Higher and lower values of CP were obtained in vegetative stage of Medicago sativa and seed ripening stage of Prangos uloptera, respectively. The highest and lowest values of EE% were found in Prangos uloptera and Astragalus spp. respectively. The highest and lowest values of CF% were obtained in the vegetative stage of Prangos uloptera and ripening stage of Medicago sativa, respectively. For NDF and ADF, the lower values were found in the vegetative stage of Prangos uloptera and Sanguisorba minor, respectively and higher values were observed in the seed ripening stage of Asragalus spp. and Prangos uloptera. The highest values of DMD and OMD% were obtained in the vegetative stage of Vicia variabilis, but the lowest values were found in Medicago sativa and Sanguisorba minor respectively. Both DMD and OMD% values were reduced from vegetation to seed ripening stage in all the species. It was concluded that it is necessary to pay attention to the seasonal changes in order to conduct the quality study and determine the nutritive value and digestibility of range plants. Use of energy and protein supplement in late period of range plant growth has been recommended for the supply of essential requirements of rangeland animals.