News

Maternal antibodies represent a form of passive immune protection transmitted from the breeder hen to her offspring (day-old chicks/DOC) through the transfer of immunoglobulins, primarily IgY, from the hen’s serum to the egg yolk. These antibodies play a critical role in protecting chicks against infections during the early stages of life, prior to the full development of their active immune system. 

Newly hatched chicks possess an immature immune system. To bridge this vulnerable phase, breeder hens transfer antibodies via the yolk as a form of passive immunity. This process is strongly influenced by the immune status of the hen, particularly through targeted vaccination designed to generate specific antibodies against selected pathogens. A comprehensive understanding of maternal antibody formation is essential in developing effective and integrated vaccination strategies for DOC. 

Mechanism of Maternal Antibody Transfer 

• Breeder Vaccination 
  Vaccinated breeder hens produce specific antibodies against vaccine antigens. The antibody titer in the hen’s serum serves as the primary determinant of the quantity of antibodies that will be transferred to the egg. Well-structured vaccination programs enhance serum antibody levels, thereby increasing the efficiency of maternal antibody transfer to the offspring. 
• Transfer to Egg Yolk 
  IgY antibodies from the hen’s serum are actively and selectively transported to the yolk during egg formation in the oviduct. IgY is the dominant isotype and reaches high concentrations in the yolk. 
• Absorption by Embryo and Chick 
  During incubation, the developing embryo absorbs maternal antibodies from the yolk into its circulatory system. After hatching, these antibodies remain in the chick’s bloodstream, providing early protection against pathogens previously encountered by the hen’s immune system. 

Factors Affecting the Effectiveness of Maternal Antibody Transfer 

• Breeder Antibody Titer 
  Maternal antibody transfer is highly dependent on the antibody concentration in the breeder hen’s serum. On average, approximately 60–70% of the hen’s antibody titer is successfully transmitted to the chick. Therefore, breeder vaccination management plays a pivotal role in determining the quality of early protection in DOC. 
• Age and Physiological Condition of the Hen 
  Breeder hens at optimal age and in good health produce eggs with higher-quality yolks and more effective antibody content. Stress, disease, and nutrition are critical factors influencing this parameter. 
• Exposure to Infection or Vaccination 
  Natural exposure to pathogens or breeder vaccination against specific infectious agents increases the levels of specific antibodies transferred to DOC. Thus, vaccination of breeder hens is a fundamental preventive strategy in integrated poultry production systems. 
• Egg Quality and Incubation Conditions 
  The stability and viability of IgY antibodies in the egg are affected by yolk quality, as well as incubation temperature and humidity. Optimal incubation conditions are crucial for ensuring efficient antibody transfer to the embryo. 

Following hatch, the maternal antibody titer in chicks is relatively high but declines exponentially over time. This decline typically follows a weekly half-life pattern, with titers decreasing by approximately 50% every 5–7 days. While maternal antibodies provide crucial early protection, they may also interfere with the active immune response to vaccination if administered when maternal antibody levels are still high. Therefore, vaccination scheduling for DOC must consider this dynamic to avoid maternal antibody interference.