Investigating the Effect of Climatic Conditions and Different Stages of Growth on the Preference Value of Bromus tomentellus in the Semi-Steppe Rangeland of Iran by Sheep

Selection of plants by livestock depends on forage and climatic conditions. In this study, the effect of climatic conditions and different stages of growth on the preference value of Bromus tomentellus for sheep in semi-steppic region was investigated. Preference value of Br. tomentellus was studied in spring and summer seasons of 2007 and 2008 in four semi-steppic sites of Sahand (East Azerbaijan), Firozkoh (Tehran), Jashlobar (Semnan) and Badamestan (Zanjan). To determine the preference value, the percentage of utilization method was used. The vegetation cover data was collected for 1 square meters in each month through random-sampling method. To compare Preference value of species in different habitats and various stages of growth, the combined analysis randomized complete block design was used. The results of this study showed that the effect of habitat factor was significant at 1% and the climatic conditions factor was significant at 5%. But, the other factors were insignificant. The results of the study showed that species composition and quantity of available forage were effective factors in the changing preference value. As a result of this, the preference value of species was variable and it depends on habitat and climatic characteristics.

Preference Index % Grazing Season % Bromus Tomentellus % Rangeland % Utilization % Livestock