In order to determine the effect of including propyleneglycol (PrGl) on plasmatic concentrations of urea and glucose as well as milk produced and solids concentration, a group of 10 cows was studied between second and fifth lactation. The animals received PrGl at 45 day postpartum during 3 consecutive days. The estimated variables were rumen degradable protein (RDP), undegradable rumen protein (URP), and net energy for lactation (NEL). The RDP average before and after administering PrGl, was 53.17 (±7.32) and 59.79 (±12.7) as a percentage of requirements, respectively. There was a statistically significant difference for the balance NEL. Regarding content solids in milk, there was no significant difference in the fat and protein percentage; however, a decrease in total amount of fat produced and a increased in the total amount protein per cow were registered. Milk production and plasmatic concentrations of glucose and urea were not affected with PrGl supply.