Bovine colostrum and milk are rich sources of immune components that are contributed by both the acquired and innate immune systems. These immune factors play a role in conveying passive immunity to the offspring and protective host immunity of the mammary gland itself. Variability in immune components in colostrum and milk are due to animal factors and management factors. Increasingly, immune components from colostrum and milk are being exploited commercially as antimicrobial agents. Moreover, vaccination procedures to boost the natural concentrations of immune components offer great potential in the development of hyperimmune milk-derived products for prophylactic or therapeutic use in humans