مقایسه افزایش وزن بره در مخلوطهای دست کاشت تحت چرا

According to climatic condition of north of khorasan, converting low productive lands under dry land farming and slopy areas to pasture lands with suitable forage species, will provide sustainable benefits and reduce soil erosion. To evaluate the importance of these pasture in liveweight gain of livestock, and determination the response to grazing of plant species, two grass species namely Agropyron desert rum and Bromus tomentallus cultivated as pure and mixed with Medicago sativa as cultivated pasture in 1995 in Sisab Research Station in north of Khorasan. So, six treatments with three replications is considered for this experiment on which the area for each poddock was 0.5 ha, and fenced by using wood and harbed wire in 1996 after plant estiblishmal. The mail weand of Kordish lambs put into paddock in may 1997 and 1998 according to pasture capacity of each paddock. The grazing period prolonged between 85 to 95 day based of available forage. Lambs were weighed fortnightly. in this experiment, the cummulative lamb weight gain of grass-legume pasture was higher than pure pasture, So the maximum and minimum liveweight of 10.5 and 8.6 kg were obtained for bromus- legume mixture and pure bromus respectively. The amount of liveweight gain of lambs were reduced during grazing period, so that in the first month liveweight gain was 6 kg/month and reached to 2 kg/month in second month and to 1 kg/month in third month of grazing. The reduction in qUantity and quality of forage espccially grasses is accounted as the main factors responsible for low weight gain in the end of experiment. The mean forage production of treatments were estimated about 2000 and 3200 kg/ha for first and second year of grazing respectively. So, the results show good perspective for using degradad lands as pasture lands.