High-quality forage in livestock feeding will significantly enhance both the yield and quality of animal products. In this respect, it is crucial to know in advance the forage quality traits to make the right choice. Accordingly, the research was fulfilled to determine forage crude protein content and the other forage quality traits in some annual plant species from different families. According to the variance analysis, it was determined that there were statistically highly significant (P<0.01) differences between the species in terms of all the of the examined traits, and the examined traits were found to be in the following ranges; dry matter content (DMC) 15.67–26.97%, crude protein (CP) content 11.93–24.11%, acid detergent fiber (ADF) content 29.54–46.488%, neutral detergent fiber (NDF) content 38.30–62.89%, digestible dry matter (DDM) contents 52.33–65.89%, dry matter intake (DMI) 1.91–3.14%, metabolizable energy (ME) 7.67–10.27 MJ kg-1 DM, relative feed value (RFV) 77.5–160.2, calcium (Ca) content 6.72–18.72 g kg-1 DM, phosphorus (P) contents varied from 3.59–5.35 g kg-1 DM, magnesium (Mg) content 2.25–4.35 g kg-1 DM, potassium (K) content 28.58– 44.40 g kg-1 DM, Ca:P ratio 1.50–4.91 and K/(Ca+Mg) (tetany) ratio 1.34–3.94. Additionally, as a result of comparing the research results with the literature knowledge, it was understood that the Ca, P, Mg and K contents of the examined species were sufficient for the livestock needs. However, due to relatively higher-level K content and lower Ca and Mg contents, the tetany (K/(Ca+Mg) ratios of grasses species, Lolium multiflorum and Triticum aestivum, were found to be over the critical value (2.2) for grass tetany illness. Thus, when livestock intensively feed forages of the grass species, risk of getting grass tetany disease would be higher than the other species. On the other hand, the biplot analysis showed that there was a positive and significant relationship between CP, DDM, DMI, ME and RFV traits, and legume family species, Lathyrus sativus, Trifolium nigrescens and Pisum sativum spp. arvense came to fore in terms of these five traits. These legume species with having higher level the most important forage quality traits, their forage quality was found quite better than the other species.