| Summary |
Forty-seven piglets, farrowed and fed by gilts and sows, were divided into 6 groups and
inoculated with a dose od LPC vaccine either by intranasal or oral route at 2 to 7 weeks of age, respectively. Piglets each inoculated by the oral route was fed with 4 ml of bovine colostrum just prior to oral inoculaton. All pigs were challenge inoculated with ALD hog cholera virulent virus by I. M. at 10 weeks old. The results showed that only 17 piglets (about 36 %) were refractory to the challenge. while another 34 piglets, from gilts and sows, were divided into 4 groups and inoculated with a dose of LPC vaccine by intranasal route or fed with bovine colostrum just prior to inoculation,· at 2 to 5 weeks of age, reapectively. All 34 pigs were challenged by the contact infection, at 10 weeks of age. The results showed that only 2 piglets (about 5.8 %) were refractory to the contact infection challenge. Either the routes of inoculation or the age, the number of farrowing of pigs seems no influence on immune response. The poor mucosa] immunity probably because the stimulation ofa immune response by a dose ofLPC vaccine was not consistently established.
Forty-seven piglets, born and fed by gilts and sows, were vaccinated by I. M. at 3 , 6 weeks of age under the current vaccination program. After second vaccination, 31 pigs were challenge inoculated with ALD virus by I. M., and another 16 pigs were challenged by contact infection, at 10 weeks of age. The results showed that all pigs (100 %) were refractory either to the I. M. inoculation challenge or contact infection. However, the current vaccination program should be tested and revised for the contaminated herds for eliminating the low incidence of hog cholera.
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