Immunity to Pasteurella multocida in protein-deficient chickens

Studies were conducted to determine the effects of dietary protein restriction on the humoral immunity (HI) and cell-mediated immunity (CMI) of chickens. New Hampshire chickens were separated into two dietary treatment groups: basal, containing 3,200 kcal/kg and 21% protein; or protein restricted (PR), containing 3,200 kcal/kg and 7% protein. In studies involving HI, half of the birds in each dietary treatment were vaccinated against fowl cholera at 4 and 8 wk of age. Blood samples were collected weekly beginning at 4 wk of age. Overall, unvaccinated birds had lower titers than vaccinated birds and PR groups generally showed lower titers than basal groups. All birds were challenged by palatine cleft inoculation of live, virulent Strain X-73 of Pasteurella multocida. The vaccinated PR group survived live challenge as well as the vaccinated basal group, but all unvaccinated birds died as a result of the challenge, regardless of antibody titer. In studies involving CMI, half of the birds in each dietary treatment were vaccinated at 5 wk of age. At 2 to 3 wk postvaccination, representative birds from each treatment were bled for total and differential blood counts. Also, birds were sacrificed and spleen cells collected. Cells were cultured in Roswell Park Memorial Institute (RPMI) medium with phytohemagglutinin-M (PHA-M), sonicated P. multocida (X-73), or RPMI only.(ABSTRACT TRUNCATED AT 250 WORDS)