Forage quality of 25 important species from summer rangelands of Nazlo Chai Basin in Urmia

Knowing that if the forage supply during grazing periods in a rangelands is sufficient for daily requirements of animal units, is one of the important factors affecting the balance between forage supply and livestock requirements in rangelands. In this regard, a study was performed and 25 range species were sampled at two growth stages (flowering and seeding) during two years. At each stage, 3 samples were collected and for each sample 5 stands were cut, and amount of crude protein (CP), dry matter digestibility (DMD) and metabolisable energy (ME) were measured in the samples in order to know the extent of critical level for daily requirements of animal units in the rangelands of Nazlo Chai Basin. For statistical analysis of the data, GLM test was applied to compare the measured factors in two years, and the sources of variations within groups were determined by Duncan test. According to the obtained results, the average amount of crud protein per unit of vegetation cover at both flowering and seeding stages was 11.5 and 9.02 percent, respectively, and these amounts were higher than critical amount of crude protein (7 percent) for maintenance requirement of one animal unit. Average amounts of forage digestibility at the growth stages were %59.86 and %54.55 respectively, and these amounts were higher than the critical amount of 50% for this factor in order to supply maintenance requirement of one animal unit. Average amount of metabolisable energy at the growth stages were 8.18 and 7.27 Mj/Kg DM which was higher at flowering stage, and lower at seeding stage than the critical amount of metabolisable energy (8MJ) for supplying maintenance requirement of one animal unit. The highest amount of crude protein (%11.33), digestibility (%60.14) and metabolisable energy (8.22Mj/Kg DM) were related to forbs, and the lowest amount of these parameters were %8.64, %52.75 and 6.97(Mj/Kg DM), respectively for crud protein, digestibility and metabolisable energy, related to grass species. Also, shrubby species contained intermediate amount of investigated forage quality factors, and the measured amounts of crude protein, digestibility and metabolisable energy in these species were %10.34, %56.72 and 7.64 (Mj/Kg DM), respectively. The results of this study are provided as basic information for the management of livestock and rangelands in the studied area and similar regions all around the country. Also this information can be useful for classification of forge quality and the methods for determination of condition, grazing capacity and trend of the rangelands.