Forage Quality of Salsola yazdiana and S. tomentosa in Different Growth Stages in Saline Desert of Yazd Province, Iran

Information on forage quality could help rangeland managers to select suitable grazing method to achieve higher animal performance without damage to vegetation. The aim of this study was to determine and compare the forage quality of S. yazdiana and S. tomentosa, which are the most important species of saline rangelands in Ardakan in Yazd province, Iran. These two species are grazed by goats and camels. The edible biomass of both species was sampled in three phenological stages during 2015-2016. Forage quality indices such as Crude Protein (CP), Dry Matter Digestibility (DMD), Metabolizable Energy (ME), Acid Detergent Fiber (ADF), Crude Fiber (CF), and Water Soluble Carbohydrate (WSC) were measured using Near Infrared Spectroscopy (NIRS). Data were analyzed using a factorial experiment in a completely randomized design. Means comparison was conducted using Duncan's Multiple Range test. According to the results, phenological stages showed significant differences for DMD, CP, WSC, ASH, ADF (P<0.01) CF and ME (P<0.05). Moreover, results showed significant differences between species for DMD, WSC, ASH, ADF (P<0.01) and CP (P<0.05). However, interactions (species × stage) showed significant differences only for DMD and ASH (P<0.05). In both species, forage quality based on positive indicators such as DMD (72.83, 63.91), CP (11.18, 10.12), and ME (7.7, 7.44) for both S. yazdiana and S. tomentosa had the highest values at the vegetative stage. By the progress of growth stages in both species, these indices were decreased. In comparison, S. tomentosa had higher forage quality than that of S. yazdiana. Although the grazing season for goat and camel in these rangelands is in fall and winter, the suitable time for grazing by these livestock is the late winter and early spring at the vegetative stage. Thus, by considering the grazing time of goat and camel from these species, supplementary feeding is required