بررسی ارزش رجحانی گونه های مرتعی و رفتار چرایی دام در مراتع نمونه پنج منطقه رویشی ایران(استان خراسان رضوی - بینالود )

Livestock selects plants during grazing in pasture and prefers some species over others. In this study, the preference value of crops in Binalud site of Khorasan-e Razavi was examined in the years 2007, 2008, 2009, and 2010 with two methods of filming the animals at the grazing time and the animals exploitation percent of each species. In the first method, the selected animal according to the dominant livestock of the region was three years old sheep and the filming was done in three times during 2 months of livestock s settlement in the area (at intervals of 20 days from the beginning of grazing in the region), each time at least 1 hour in 2 to 3 times during the day shooting the grazing of the livestock. The results of time spent on grazing of each species were analyzed using SAS software in a randomized complete block design and mean comparison was performed by Duncan method. In the second method, the production and consumption of livestock grazing species were considered. First, an area of about 1 hectare was selected in which the vegetation cover was more similar to the whole pasture and in order to prevent the entrance of the livestock it was limited with fence. The production was measured inside the limited area and the consumption was measured outside of the grazed block. Then the preference value index was accounted according the amount of livestock s consumption of each species. The results were again analyzed using SAS software in a randomized complete block design and mean comparison was performed by Duncan method. The species were separated in 5 degrees according to the preference value index. Also the grazing manner of livestock was analyzed by installation of GPS on it during 24 hours in three levels during the grazing season and with analysis of recorded inputs of SAS software in a randomized complete block design and mean comparison was performed by Duncan method. According to the results of the feeding minutes, species are categorized in three categories: 1- Species which are always grazed. Among these species of Convolvulus arvensis ، Scariola orientalis and most of the annual species and forbs can be named. 2- Species which are grazed only in a specific level of their life period including species of Onobrychis cornata whose flowers at the beginning of spring are really interesting for livestock and Iris songarica which is grazed at the time when its leaves turn yellow and are growing dry. 3- Species which the livestock has more interest in eating them at the initial of growing and with time passing and the crops losing their moisture their preference value is decreased slowly. Most of grasses like Agropayron intermedium and Bromus kopetdaghensis. Results of the production and consumption method is completely based on the amount of livestock s pressure on pasture. Meaning, the more the livestock grazes the crops, that crop is considered as the most palatable crop. Totally, species were categorised in 4 levels from the degree of 2 to 5. Also the GPS outputs specified that in addition to the distance taken by the livestock, with the decrease of the amount of forage the average speed is increased. There was also a significant difference between the distance taken in different slopes and sheep preferred the lower ones. Key words: species preference value index, feeding minute s method, filming, exploitation percent, livestock s grazing manner, GPS