بررسی خصوصیات رویشی گیاهان جامعه درمنه-شال دم و رفتار چرایی دام بر آنها

Extensive areas of desert range in central plains of Iran are the sole source of forage for sheep and goats during the winter and early spring grazing season.To obtain basic information on the production and utilization of range forage and sheep herd,s nutrient requirements in months of grazing season in tempetrate steppic rangelands , a study was conducted on a typical desert range in Roudshour in 2005.This area is characterized by cold and wet winter and a warm and dry summer.The growing season extends from late February to late September, with moist and warm spring.Peak of green phytomass was recorded in April. The grazing season extends from late December to mid- May . The evaluation of preference value and desirability of range plants are important subjects in range management. The changes of preference value and desirability of range plants were studied since 2005 for 2 years. The knowledge of animal grazing behavior and indigenous grazing systems are very important in range management specially in arid range lands. The animal grazing behavior and indigenous grazing systems were conducted in 2004. The treatments were starting and ending of grazing, the times consumed for daily grazing and rest , the velocity of herd movement , monthly food requirement of herd, and current grazing systems. Each treatment was studied by standard methods. Digestible nutrient requiremens for sheep herd was calculated by using the NRC(1985) method.The production and utilization of forge were determined by the cage method used by klingman et al.(1943). The preference value and desirability of range plants studied for each month during grazing season .The percent of intaked forages by animal were used for determining the preference value and desirability of range plants. the production and utilization of range forage and sheep,s nutrient requirements in months of grazing season were different and the available forage in January , February and March was less than sheep,s nutrient requirements but in April and May was more than the herd,s requirements. t the preference value and desirability of range plants for Afshari race sheep differed between plant species and months of grazing season. Results showed that the Roud e shour range lands grazed since early January for 5 months. When the forge of range lands is shortage a kind of continuous grazing system was applied and conversely, when the forage is plenty a rest rotation grazing system was used .The times that animals spend in range land affected by available forage and climatic conditions. In cold months of grazing season specially January, the animal had the least audience in rangeland but the most movement. Conversely, in warm months , had the lowest movement and the highest audience.The food requirement of the herd, changed in grazing season. The TDN requirements of a 500- head herd differed 23469, 25980, 28770, 30909 and 20606 kg January, February , March , April ,and May respectively. Key words : Daily grazing and rest of herd , forage production , forage utilization , grazing season, indigenous grazing systems, movement of herd, preference value , plants desirability, Roudshour , sheep herd's nutrient requirements

کلیدواژه ها:

خصوصیات رویشی ، علوفه ، دام ، آب و هوا ، شال دم ، منطقه رود شور ، سیستم چرا ، درمنه