Investigation of forage quality index of some range species and comparison with their critical levels for daily requirement of grazing animal in estepi rangelands of Sabzevar

Management of animal nutrient and stocking rates depend on nutritive value and nutrition requirements of grazing animal. Determination of nutritional value of forages is one of the necessary factors in grazing capacity. In this study، seven plant species including Seidlitzia rosmarinus، Stipagrostis pennata، Salsola richteri، Halathamnus glaucus، Astragalus squarasus، Salsola arbuscula and Reaumuria fruticosa as considerable components of rangelands vegetation in the region، were collected during three phonological stages (vegetative growth، flowering and seeding stage) in 2008. Then، forage quality index including Crude Protein، Acid Detergent Fiber، Dry Matter Digestible and Metabolism Energy were determined and compared with their critical levels. In order to data analysis، split plot statistical method with randomized complete design in 3 replication of 21 treatments for each location، was used. In order to find the sources of variations within groups، Duncan test was employed. Results showed that mean crude protein amounts at vegetative growth and flowering stages are higher and at seeding stage are lower than its approximate amount of critical level (7%) for supply the daily requirement of animal unit. Mean amounts of digestibility at different growth stages are higher at all phonological stages than its critical level (50%) for one animal unit maintenance. Metabolism energy amounts at vegetative growth and flowering stages are higher and at seeding stage are lower than its approximate amount of critical level (8 Mj) for supply daily requirement of animal unit. Results also showed that، in active growth and flowering stages، forage contain metabolism energy، crude protein and dray matter digestibility، were more than critical levels. Which provied، daily requirement of grazing livestock in maintenance provide. But in maturing stage، their values were low than critical levels and daily requirement of grazing livestock can not be provided. Therefore، live animal weight and economical performance will reduce. So it is recommended that according to range condition and costs، of feed schematization and nutrition supplements are used for reaching animal favorite performance.