Deciphering the colostral-immunity transfer: from mammary gland to neonates small intestine

Colostrum, the initial mammary secretion produced by various mammals following birth, is a conduit for maternal immunity transfer in diverse mammalian species. Concurrently, many cellular processes are occurring in the neonatal small intestine to prepare it to receive molecular signals from a superfood essential for the neonate's health and development. During the prepartum colostrum secretion, the newborn intestine undergoes transient alterations in the intestinal barrier, primarily regulating immunoglobulin absorption. Accordingly, the immunity transfer can be delineated in two stages: the initial stage, which occurs on the maternal side (colostrogenesis serves as the primary immunoglobulin source), and the subsequent stage, which appears on the newborn side (the gut closure). The interval between the two stages is of great consequence, influencing the extent of immunity absorption and, thus, the newborn's health outcomes. The dual-phase (maternal-neonatal) process of immunity transport intersects with numerous factors, including cellular receptors such as the neonatal Fc receptor (FcRn), endocrine factors, physiological cellular phenomena (such as the blood-milk barrier), and environmental circumstances. However, no previous discussions have investigated the immunity transfer to neonatal health, nor have they discussed both sides. This gap highlights the necessity for further investigation into the time-dependent process, which can be described as a race against time to transfer adequate immunity (in quantity and quality) to neonates. Accordingly, the review encompasses a comprehensive analysis of immunological studies, from their foundational stages to the latest molecular research conducted on various mammalian species. This review aims to discern patterns and draw comparisons that advance our understanding of the complex interplay between colostral immunity transfers from diverse view points, including veterinary science and immunology.