The gastrointestinal tract of neonatal calves is relatively mature but still requires morphological and functional changes. The intake of colostrum with its nutrient and non-nutrient components exerts marked effects on gastrointestinal development and function. Colostrum intake provides immunoprotection (passive immunity by immunoglobulins) and is essential for survival of neonates of most species. Furthermore, there are important transient as well as long-lasting systemic effects on the nutritional status, on metabolism, and on various endocrine systems due to intake of nutrient and non-nutrient colostral components that contribute to survival in the stressful postnatal period. Colostrum is much more than just a supplier of immunoglobulins.