Importance of Prenatal Development and Colostrum in Neonatal Adaptation of Dairy Calves: Implications for Metabolism, Transfer of Passive Immunity, and Environmental Modulation

Abstract Traditionally, colostrum management and neonatal research focused primarily on transfer of passive immunity, with colostral immunoglobulin G (IgG) concentration serving as principal indicator of colostrum quality. However, increasing evidence indicates that neonatal adaptation is regulated by a considerably more complex physiological network. The calf enters extrauterine life with a maternally shaped physiological starting point resulting from prenatal nutrient supply, placental exchange, maternal metabolic status, and environmental exposure during late gestation. Following birth, colostrum becomes the primary biological interface through which nutritional, endocrine, immunological, and developmental signals interact with the neonatal organism. Beyond immunoglobulins, bovine colostrum provides a complex source of nutrients and bioactive factors that influence intestinal maturation, nutrient utilization, metabolic homeostasis, thermoregulation, epithelial adaptation, and early-life resilience. Special importance appears to reside in the interaction between colostral components and the developing gastrointestinal tract. During the immediate neonatal period, the intestine simultaneously functions as a digestive, absorptive, endocrine, immunological, and barrier organ while undergoing rapid postnatal maturation. Consequently, passive transfer of immunoglobulins should be interpreted as part of more complex absorptive and developmental processes rather than a simple reflection of colostral IgG concentration alone. This review summarizes current knowledge regarding maternal metabolic priming, colostrum-derived nutrient and bioactive signaling, intestinal development, passive transfer, and environmental modulation in neonatal calves. Collectively, the available evidence supports a systems-level framework in which colostrum should be understood not merely as an antibody source, but as an integrated biological regulator of neonatal adaptation during early life.