The processes of formation of the local protection of the respiratory tract in nasal secretion samples of Holstein calves from birth to 6 months of age that were born from clinically healthy cows were examined. Only clinically healthy animals were involved in the experiment. Nasal secretion samples were collected with the help of a sterile foam tampon with a fixing thread in order to assess local immunity in animals at the age of 1, 5, 10, 30, 60, 90, 120, 150, and 180 days. Total protein, mucin, lysozyme activity, and alkaline phosphatase (ALP) were determined using commercially available methods. The amounts of immunoglobulins were studied using disk electrophoresis in polyacrylamide gel with commercial marker proteins. Studies have shown that the primary potential of local protection of the respiratory tract is formed during intrauterine development. The main factors of primary potential are mucin, lysozyme, alkaline phosphatase, and secretory immunoglobulins of classes A (SIgA) and M (SIgM), which provide safety of adaptation in newborns to the new conditions of existence. There is a decrease in mucin level by 47.3% (P 0.05) at the age of 60 days and mucin level increases by 56.7% (P