Page 726 - Veterinary Immunology, 10th Edition

transfer across the placenta as in primates, or by ingestion of immunoglobulin-
VetBooks.ir • Understand the immunological properties of colostrum and milk.
rich colostrum.

• Describe the absorption of colostrum from the neonatal intestine.
• Understand how colostrum protects against septicemic infections while milk
protects against enteric infections.

• Understand the reasons for failure of passive transfer.
• Understand the principles of diagnosing and treating failure of passive transfer.
• Define colostrum and passive transfer.

• Understand why young mammals cannot be successfully vaccinated.
• Understand the role of the microbiota in the development of the neonatal
immune system.

When a mammal is born, it emerges from the sterile uterus into an
environment where it is immediately exposed to a host of
microorganisms. Its surfaces, such as the gastrointestinal tract,
acquire a complex microbial flora within hours. If it is to survive,

the newborn animal must be able to control this microbial
colonization. In practice, the adaptive immune system takes some
time to become fully functional, and innate mechanisms are
responsible for the initial resistance to infection. In some species

with a short gestation period, such as mice, the adaptive immune
system may not even be fully developed at birth. In animals with a
long gestation period, such as large domestic mammals, the
adaptive immune system is fully developed at birth but cannot

function at adult levels for several months. The complete
development of adaptive immunity depends on antigenic
stimulation. The development of B cells and B cell receptor (BCR)
diversity requires clonal selection and antigen-driven cell

multiplication (Chapter 15). Thus newborn mammals are
vulnerable to infection for the first few weeks of life. They need
assistance in defending themselves at this time. This temporary
help is provided by the mother's milk in the form of antibodies and

possibly T cells. The passive transfer of immunity from mother to
newborn is essential for survival.

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