Research Information Following the improvement of animal welfare,more and more people regard pets as families.With update and progress of the veterinary clinical medicine, pet's lifespan prolongs obviously. Classical swine fever (hog cholera) is one of the most important infectious diseases of swine in Taiwan. LPC live vaccine has been used for the prevention for many decades. However, its efficacy in young pigs will be interfered tremendously by maternal antibody, which derives from vaccinated dams. Subsequently, the antibody level in young pigs depends on the antibody level of sows. Currently there are 3 different vaccination programs have been recommended for sows. The sows are either vaccinated only once before the first breeding or vaccinated once before every other breeding or vaccinated once before every breeding. We are interested to find out which vaccination program interferes the most for the vaccine.