Forage quality of range species and daily requirement of Sanghesary sheep in Firozkhoh mountain rangelands

    Knowledge of the animal daily requirement in rangelands is one of the essential requirements to calculate the grazing capacity in rangeland plans. In this regard, the daily metabolizable energy requirements of different Sangesary sheep (ewe, ram, and lamb) were investigated. For this purpose, according to the average values of forage quality indices and the proportion of species in the plant composition, the amount of metabolizable energy in one kilogram of dry forage at different growth stages was estimated, and considering the daily metabolizable energy requirement, the amount of forage that supplies the animal was estimated. The daily metabolizable energy requirement was calculated according to the proposed MAFF (1984) equation under grazing condition regarding the physical properties of the rangelands, water distribution intervals, plant density, and applying an incremental coefficient of 70%. Based on the results, the amount of forage needed to meet the daily needs of the ewe of the Sangesary sheep with a mean weight of 37 kg in the early, mid, and late growing season was estimated to be 1.6, 2.1 and 2.3 kg dry matter, respectively. The values for adult rams with an average weight of 48.75 kg were estimated to be 1.9, 2.5 and 2.9 kg in different growth stages. The lambs' daily requirement with an average weight of 19.88 kg was estimated to be 1.3, 1.7, and 1.9 in each growing season. The results showed that considering the amount of 1.5 kg of dry matter forage to meet the daily requirements of different kinds of animals grazing in rangelands is not correct and animal requirement need be determined based on forage quality in phenologiacal stages.In addition, the results emphasize that in order to adapt the daily requirements of animal to the forage quality, it is necessary to consider the values of forage quality indices and the proportion of all species grazed in the plant composition, so that the results should not be limited to the species in animal diet. Otherwise, as in the present study, the estimated requirement is more than the daily intake of animal grazing on rangelands.