The transfer of passive immunity is essential to ensure the health and welfare of new-born calves. Although the dynamics of serum Ig concentrations in these animals are well-described, data about saliva Ig are limited. This study aimed to evaluate serum and saliva Ig (i.e., IgG, IgA, and IgM) concentrations during the first week of life in healthy and sick calves. Blood and saliva samples were collected from 20...