 of birds in different treatment groups at 0d-post-*S*. Heidelberg challenge.  ![](pone.0000000.t000){#pone.0000000.t000g}    Sample               000 μl      00 μl   0 μl   Colonies counted (00^−0^)   MPN index/g   Log00   Average MPN value   SEM   -------------------- ----------- ------- ------ --------------------------- ------------- ------- ------------------- ------   Control              0           0       0      0                           0             0       0.00                0.00   0                    0           0       00     00                          0.0                                          0                    0           0       0      0                           0                                            0                    0           0       0      0                           0                                            0                    0           0       0      0                           0                                            0                    0           0       00     00                          0.0                                          CNP                  0           0       0      00                          00            0.0     0.00                0.00   0                    0           0       0      0                           0                                            0                    0           0       0      0                           0                                            0                    0           0       0      0                           0                                            0                    0           0       0      0                           0                                            0                    0           0       0      0                           0                                            Commercial Vaccine   0           0       0      0                           0             0       0.00                0.00   0                    0           0       0      0                           0                                            0                    0           0       0      0                           0                                            0                    0           0       0      0                           0                                            0                    0           0       0      0                           0                                            0                    0           0       00     00                          0.0                                          *P-*value            *P\>*0.00                                                                                          At 0d of age, chickens were orally vaccinated with either PBS (NV), 0000 μg chitosan nanoparticle vaccine (CNP) or a commercial vaccine (CV). The same route of delivery and doses was repeated at 0d of age. At 00d of age, birds were challenged with 0 X 00^0^ CFU/bird of either *S*. Enteritidis or *S*. Heidelberg. At 0d-post-challenge *S