The objective of this study was to investigate the nonlinear relationship between altered carbohydrate (CHO) traits and predicted truly absorbed nutrient supply to dairy cattle in hull-less (hulless) barley. Four cultivars were developed at the Crop Development Centre, University of Saskatchewan, with differences in carbohydrates traits on the basis of amylose (1–40% DM) and β-glucan (5–10% DM) content. All cultivars were planted and grown in Saskatchewan (Canada) and then harvested in 3 consecutive years. The digestion in the rumen and intestine was determined used in situ dairy cows with a randomized complete block design (RCBD) with samples year as a random block effect. The rumen degradation was carried out with in situ nylon bag technique. The intestinal digestibility was carried out with 3-step in vitro technique with 16 h of pre-incubation. The truly absorbed nutrient supply to dairy cattle was evaluated using the Dutch protein evaluation system (called DVE/OEB in Dutch). The data from RCBD experiment design were analyzed with Proc Mixed of SAS. Results showed that OM fermented in the rumen (FOM), undigested inorganic matter (UASH), total protein supplied to the small intestine (TPSI), metabolizable protein (MP), microbial protein synthesized in the rumen based on available N (N_MCP) and truly absorbed microbial protein in the small intestine (AMCP^DVE) had cubical relation with amylose to amylopectin ratio (A:AP) and the β-glucan level. Digested (DOM) and undigested organic matter (UOM), undigested dry matter (UDM) and endogenous protein in the small intestine (ENDP) showed quadratic relation with the ratios of A:AP and the β-glucan levels. Truly absorbed protein in the small intestine (ABCP ^DVE) and degraded protein balance (OEB ^DVE) were quadratically related to the A:AP and cubically related to the β-glucan level. In conclusion, the predicted truly absorbed protein supply to dairy cows from the hulless barleys had curve-linear relationship with the altered carbohydrate traits. Further study on dairy milk production performance is needed.