1. Taiwan Provincial Research Institute for Animal Health, Tamsui, Taiwan.
2. Department of Veterinary Medicine, Na-tional Chung-Shin University Taichung, Taiwan.
3.Council for Agricultural Planning and Development, Taipei, Taiwan.
Piglets with maternal antibody titers of 1:32 or b low receiving one dose of LPC-Chiuese (HC) strain of hog cholera (HC) ncclne virus containing 100 pig infective doses (PID) survived normally after challenge with virulent HC virus. Maternal antibody titers between 1:32 and 1:64 sunhed with clinical aad histopathological reactions. However, maternal antibody titers above 1: 64 died after virulent challenge. Epizootiological data indicated that 1 to 4 weeks old piglets with maternal antibody titers below 1:32 were 69%,
75%, 95% and 97% respectively. Experimental data suggest that the optimal vaccination age is 3 weeks old, about 95% vaccinated piglets will gain solid Immunity.