عنوان مقاله [English]
In order to calculate the grazing capacity in range management plans is nessoceary to be aware about daily metabolizable energy requirement of livestock in rangelands at different climatic zone. In this regard, daily metabolizable energy requirement of Ghezel sheep in Sahand mountain rangelands were studied. According to the average values of forage quality indexs in plant species and their proportion in the composition of rangeland vegetation in different growth stages, metabolizable energy value in one kilogram of dry matter for livestock grazing rangelands was estimated and considering of daily metabolizable energy required of Ghezel sheep in Sahand mountain rangelands, amount of forage which supplies animal requirements in different stages of growth, were estimated. Daily requirement of ram, ewe and lambs of Ghezel sheep based on metabolizable energy, according to the MAFF equation (1984) proposed in the state of maintenance and livestock grazing in rangeland and considering the physical characteristics of the rangelands, intervals of animal drinking places, plants density and 60% additive coefficient, were calculated 14.25, 18.82 and 10.75 Mj respectively. According to the results, amount of forage required to provide the daily requirements ram, ewe and lambs of Ghezel sheep considering the forage quality of rangelands in 2008, in the initial stages of growth respectively is 1.61, 2.13 and 0.93; in the middle of stages growth respectively is 1.83, 2.42 and 1.06 and in the final stages of growth is 2.24, 2.96 and 1.30 Kilograms of dry forage. The amount of forage for 2009 in the initial stages of growth is 1.57, 2.08 and 0.91; in the middle of stages growth is 1.73, 2.28 and 1.00 and in the final stages of growth is 2.23, 2.94 and 1.29 Kilograms. Also, amount of forage required to provide the daily requirements ram, ewe and lambs of Ghezel sheep considering the forage quality of rangelands in 2010, in the initial stages of growth is 1.55, 2.04 and 0.90, respectively; in the middle of stages growth is 1.82, 2.40 and 1.06 and in the final stages of growth is 2.23, 2.94 and 1.29 Kilograms of dry forage, respectively. This implies that time grazing affects on the daily requirements of livestock and needed those daily requirements to be determined according to forage quality in of each stage. Obviously, depending on the conditions years it may some be changed quality of the forage plants but since the determination of forage quality is expensive, the results obtained can be used to estimate daily requirement use of livestock in the different years.