Hematologic profiles and development of innate immune function in healthy Holstein calves during the pre-weaning period.

Background: The development and state of innate immune cell function during the first 90 days of life in dairy calves have not been fully described.

Objective: This transversal study attempted to examine the changes that occur in circulating blood cells and the innate immune response in healthy calves from birth to 89 days of age.

Methods: Healthy Holstein calves represent three windows of development, G1 from 1 to 7 days old (n = 26), G2 from 30 to 40 days old (n = 28), and G3 from 60 to 89 days old (n = 36) were sampled once each from a single herd.