All the animals were intramuscularly inoculated with 0.5 mL of Pasteurella multocida oil adjuvant vaccine after 135 days of experimental feeding. Observing all aseptic precautions 2 mL of blood sample was collected by jugular venipuncture at 0, 7, 14, 21, 28 and 35 days of post exposure to antigen from all the animals in the morning (before watering and feeding)in clean labelled tubes, kept in slanting position for 45 min, followed by centrifugation at 700 × g for 15 min to separate out serum. The harvested serum was carefully transferred to the clean labelled 2 mL plastic vials and stored at −20◦C for further analysis.