Fig. 1

OD values and HI titres of serum samples from all 180 gilts and sows depending on parity and applied vaccine. OD: optical density; red dotted line: OD-value of 0.3 representing the threshold of the applied ELISA
OD values and HI titres of serum samples from all 180 gilts and sows depending on parity and applied vaccine. OD: optical density; red dotted line: OD-value of 0.3 representing the threshold of the applied ELISA