Glucagon-like peptide 1 (GLP-1) plays a role in the regulation of appetite and glucose homeostasis via the stimulation of insulin secretion. The objective of this study was to evaluate the effect of extended colostrum feeding on plasma concentrations of GLP-1. Holstein bull calves (n = 18) were fed pooled colostrum at 7.5% of BW at 2 h after birth, then fed mature milk (M), mixture at a ratio of 50:50 for pooled colostrum and milk (CM), or pooled colostrum (C; n = 6 for each treatment) at 5% of BW at 12 h after birth, and every 12 h thereafter until 72 h after birth. Blood samples were obtained before (1 and 2 h after birth) and after (until 75 h after birth) the first colostrum feeding, and plasma concentrations of GLP-1, insulin and glucose were measured. Data were analyzed by ANOVA of JMP 13 with treatment, time and treatment by time interaction as fixed effects. Treatment by time interaction was observed for plasma insulin and glucose concentrations (P < 0.01), which was mainly the result of lower concentrations from 14 to 27 h after birth (from 1 to 2 d after birth) for CM or C than for M. Conversely, on 3 d after birth, difference between treatments was not observed for insulin and glucose. Plasma GLP-1 concentration tended to be higher (P = 0.05) for C (2.26 ± 0.24 ng/mL; LSM ± SEM) compared with M (1.37 ± 0.24 ng/mL). A treatment by time interaction was observed for GLP-1 (P < 0.01), but unlike glucose and insulin, this was mainly the result of higher concentrations from 54 to 70 h after birth (3 d after birth) for C than for CM or M. Plasma concentration of glucose was not correlated with that of GLP-1 but positively correlated with that of insulin on d 1 (r = 0.48, P < 0.01) and d 2 (r = 0.49, P < 0.01) after birth. On 3 d after birth, plasma concentration of insulin was not correlated with that of glucose but positively correlated with that of GLP-1 (r = 0.34, P < 0.01). In conclusion, these results indicate that extended colostrum feeding may increase plasma GLP-1 concentrations, especially on 3 d after birth, but further study is necessary to determine the effect on plasma insulin and glucose concentrations.