A metabolism trial was conducted to compare the nutritional value of: 1)"Quickstand" bermudagrass [Cynodon dactylon (L.) Pers.], 2)caucasian bluestem [Bothriochloa caucasia (Trin.) C.E. Hubb], 3)tall fescue (Festuca arundinacea Schreb.), and 4)orchardgrass (Dactylis glomerata L.). The warm-season grasses (bermudagrass and bluestem) were higher (P < .01) in fiber components than the cool-season grasses (tall fescue and orchardgrass). Bluestem was lower (P < .001) in CP, hemicellulose, and ash, and higher in NDF (P < .001), ADF (P < .001), cellulose (P < .001), and lignin (P < .01) than bermudagrass. The warm-season grasses were lower in the apparent digestibility of DM (P < .001), NDF (P < .01), ADF (P < .05), cellulose (P < .05), and hemicellulose (P < .01) than cool-season grasses. Apparent digestibility of NDF (P < .001), ADF (P < .001), cellulose (P < .01), and hemicellulose (P < .01) was higher for bluestem than bermudagrass. Fescue was higher (P < .001) in apparent digestibility of DM and CP and lower (P < .01) in apparent digestibility of NDF, ADF, cellulose, and hemicellulose than orchardgrass. Lambs fed bluestem had lower (P < .05) N retention than those fed bermudagrass, when expressed as g/d. Lambs fed fescue had higher (P < .001) N retention, than those fed orchardgrass. When expressed as a percent of intake or absorption, N retention values were similar among treatments. The results of this study suggest that cool-season grasses are of higher nutritional value than warm-season grasses.