Colostrum, the yellowish fluid, secreted by mother during the initial days of lactation is very essential to impart immunity to the new born infants because it contains

Colostrum is essential to impart immunity to the newborn infants because it contains a high concentration of immunoglobulin A (IgA).
IgA plays a significant role in imparting immunity to the newborn. IgA is an antibody that plays a vital role in protecting the mucous membranes of the body, including those in the respiratory and digestive tracts. It helps prevent pathogens from entering the body through these mucosal surfaces. IgA, which is transferred from the mother to the newborn through breastfeeding, provides temporary protection to the infant’s mucosal surfaces, boosting their immune system and providing defense against infections.
(2) Natural killer cells are not found in colostrum. They are a type of lymphocytes that are primarily involved
In recognizing and eliminating virus-infected cells and cancer cells.
(3) Monocytes are not a component of colostrum. They are a type of WBC that can differentiate into macrophages or dendritic cells. They are phagocytes.
(4) Macrophages are not typically found in colostrum. They are phagocytic cells that engulf and destroy pathogens, dead cells and cellular debris. They also serve as antigen-presenting cells.