چكيده لاتين :
Determination of nutritional value of rangeland species is one of the fundamental factors for evaluation of grazing capacity and management of rangelands. This research was performed to determine the nutritional values of Halocnemum strobilaceum and Halostachys caspica and study the effects of different phenological stages (vegetative, flowering, seeding) on chemical composition in these species during 2015 in north-western rangelands of Golestan province. Plant sampling was completely randomized and nutritional values indicators including crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber(NDF), digestible dry matter (DMD), ash, Ether extract, metabolic energy (ME), dry matter intake(DMI), relative feed value(RFV) and mineral elements (sodium, potassium, magnesium, calcium, phosphorus, copper, zinc, iron and manganese) were measured. After analysis of variance, Duncan's multiple range test were used to compare the mean of studied indices for each species and t-test was used to compare the two species at different phenological stage and mineral elements with their critical levels. The results showed that crude protein, ADF, NDF, DMD, ash, EE, ME, DMI, RFV, sodium, potassium, magnesium, calcium, phosphorus, copper, zinc, iron and manganese were different significantly in different phenological stages (p<0.05). With the growth progress, ADF and NDF increased but crude protein, DMD, DMI, ME and RFV decreased significantly in both species (P<0.05). H. caspica had better quality than H. Strobilaceum (RFV: H. caspica> H. strobilaceum). The content of sodium, potassium, magnesium, calcium, copper, iron, manganese measured at different growth stages, were more than critical level for ruminants; however, the content of phosphorus and zinc were less than critical level. In general, mineral elements of two species are provided all the elements that livestock need, except zinc and phosphorus.
