Final answer:
Colostrum contains Immunoglobulin A (IgA), an antibody important for the protection of infants from disease, present in breast milk and mucosal secretions.
Step-by-step explanation:
Colostrum contains the antibody Immunoglobulin A (IgA). IgA is present in mother's breast milk and plays a crucial role in protecting infants from disease by preventing the entry of pathogens through mucosal surfaces such as the respiratory and gastrointestinal tracts.
IgA functions in two forms: a four-chain monomer in the blood and an eight-chain dimer in exocrine gland secretions. This dimeric form of IgA, found in colostrum, protects body surfaces exposed to the external environment by being secreted in mucosal secretions like saliva, tears, and breast milk.
The ability of colostrum to provide critical initial immunity to newborns highlights the importance of breastfeeding in the early days of an infant's life. This early nutrition and immune support is key to the development of a strong immune system in infants.