Forage quality of important range species in summer rangelands of Saraliabad

Knowledge of forage quality is of paramount importance for livestock and rangeland management. For this purpose, the forage quality of range species was investigated in summer rangelands of Saraliabad, Golestan province to meet daily animal unit requirement. In the present study, 12 rangeland species including Achillea millifolium, Agropyron trichophorum, Centurea zuvandica, Crepis khorassanica, Koeleria cristata, Medicago sativa, Poa angustifolia, Taraxacum brevidens, Thymus transcaspicus, Tragopogon graminifolius, Trifolium repens and Artemisia aucheri were sampled at three different phenological stages (vegetative, flowering and seeding) in 2009. In each stage, three samples and for each sample three individuals were cut. Then, forage quality indices were calculated. Results showed that the crude protein values at all growth stages were higher than the critical level (7.0%) to meet daily animal unit requirement. In addition, dry matter digestibility values in vegetative and flowering stages were higher than the critical level (50%) to meet daily animal unit requirement, contrary to the seeding stage. Metabolisable energy values in vegetative stage were higher and in flowering and seeding stages were lower than the critical level (8Mj) to meet daily animal unit requirement. Our results clearly showed that the forage quality of range species varied at different growth stages, indicating that daily animal unit requirement need be determined based on forage quality. The results of this study could be used in determining the daily animal unit requirement in different years since measuring forage quality is costly.