The basis for sustainable dairy production is set in the newborn heifer calf. Earlier research has demonstrated that weight gain and health during early life influence the adult calf's production capacity, partly an effect of nutrition. Probably the microbiota in the gastrointestinal tract (GIT) also is of importance for the growth and health of the calf. It has been indicated that the microbiota in the GIT influence the immunlogical status and the microbiota in the respiratory tract in the newborn calf. In this project we will study if the colostrum feeding routine (bottle feeding, calf suckling or feeding by an esophageal tube) influence the development of the microbiota in the GIT and respiratory tract. New methodology makes these studies possible. The hypothesis is that the microbial interaction in the GIT and respiratory tract is significant for the calf's future capacity for sustainable production as well as the routine of colostrum feeding for the development of the microbiota.