Specific and innate immune factors associated with the mammary gland tissues and secretion play a vital role in protecting the gland from infectious diseases. In recent years, considerable research effort has been focused on enhancing the natural defence mechanisms of the mammary gland during periods of susceptibility to a disease. This paper deals with investigations on the mammary gland health status associated with lactoferrin level and the somatic cell count in the milk during the housing and grazing period. The following conclusions were made: during the grazing period the lactoferrin concentration in the milk is significantly lower than that in the housing one. The main reason of the increase of the somatic cell count when transfering cows from the housing to the grazing period, is non-infectious udder irritations indicated by the low level of lactoferrin concentration during that time.