Immunity to Pasteurella multocida in protein-deficient chickens

Area of Science:

• Immunology
• Animal Nutrition
• Poultry Science

Background:

• Dietary protein is crucial for immune function.
• Understanding protein restriction's impact on chicken immunity is vital for poultry health.
• Humoral immunity (HI) and cell-mediated immunity (CMI) are key immune components.

Purpose of the Study:

• To investigate the effects of dietary protein restriction on chicken humoral and cell-mediated immunity.
• To assess the protective effects of vaccination against fowl cholera under protein restriction.
• To evaluate immune responses following challenge with virulent Pasteurella multocida.

Main Methods:

• Two dietary groups: basal (21% protein) and protein-restricted (PR, 7% protein).
• Vaccination against fowl cholera at 4 and 8 weeks (HI studies) or 5 weeks (CMI studies).
• Blood sampling, challenge with Pasteurella multocida Strain X-73, and spleen cell culture with PHA-M or P. multocida antigen.

Main Results:

• Protein-restricted groups generally showed lower antibody titers than basal groups.
• Vaccinated PR birds survived Pasteurella multocida challenge similarly to vaccinated basal birds.
• Unvaccinated birds, regardless of antibody titer, succumbed to the challenge.

Conclusions:

• Dietary protein restriction can lower antibody titers but does not abolish protective immunity.
• Vaccination confers significant protection against virulent Pasteurella multocida challenge, even under protein restriction.
• Immune competence, particularly protective immunity, is maintained to a degree despite reduced dietary protein.