Comparative study of Astragalus effusus Bunge forage quality in three growth stage and management system

Estimation of forage quality is one of the most important fundamental prerequisites to determine daily animal requirement as well as rangeland capacity for better management of rangeland. Milk-vetch (Astragalus effusus Bunge.) is a native perennial forage species of cold mountainous rangelands which its forage quality and quantity is important to provide animal nutrition needs. This type of astragalus (A. effusus), due to palatability and high preference values, has been overgrazed by animals. To compare grazing effects on forage quality of Astragalus effusus in three management system [forbidden grazing (FG), rest rotation grazing (RRG) and continuous grazing (CG)] and different plant phenology stages [vegetative growth, flowering and seeding stages], amount of crude protein(CP), acid detergent fiber(ADF) and digestible dry matter(DDM) measured in laboratory. Our results showed forage quality decreased with plant growth in all three managerial systems, and vegetative growth stage displayed highest forage quality. Significant differences were observed between nutritional value indices in various development stages and all three management practices. The highest forage quality and plant health is obtained in RRG system.