The objective of this study was to determine the changes in hay yield and quality components at different phenological stages of a bulbous barley (Hordeum bulbosum L.) population handpicked from natural flora during 20032007 in Samsun, Turkey. The phenological stages of bulbous barley during spring-summer (grazing maturity, early heading, heading, and milk-dough) and autumn (early growing) were investigated. Significant differences were observed in hay yield, relative feed value (RFV), crude protein (CP), acid and neutral detergent fiber (ADF and NDF), Ca, Mg, K, P, Mn, Fe, and Zn concentrations, and K(Ca + Mg)(-1) and Ca P(-1) ratios of DM, depending on development stages. Hay yield, ADF, NDF concentrations, and the Ca P(-1) ratio increased, whereas RFV, CP, Ca, Mg, K, P, Mn, Fe, and Zn concentrations, and the K (Ca + Mg)(-1) ratio in DM decreased as plant development progressed. The Cu concentration was inconsistent at all phenological stages. The results of this research indicate that harvesting or grazing should not be delayed in order to obtain the maximum benefit of bulbous barley hay. Additionally, while some minerals were inadequate, others were in excess, in terms of healthy feeding, at all development stages. Therefore, additional supplementation with some minerals is needed for bulbous barley-based ration or bulbous barley should be grown in mixtures with legumes for feeding productive livestock.