Abstract
The changes in serum total protein and immunoglobulin levels, and BVD, IBR and PI-3 viral neutralizing antibody titers in colostrum-conferred Korean native calves during the first 12 weeks postpartum were studied, and the results obtained were summerized as follows: The Mean concentration of total protein, total immunoglobulin, IgG, IgM and IgA in sera of 9 calves at birth were $3.8{\pm}0.5g/dl$, $0.27{\pm}0.15mg/ml$, $0.06{\pm}0.08mg/ml$, $0.21{\pm}0.11mg/ml$, and extremely low concentration, respectively. Serum total protein level reached a maximum at 20 hours after birth, total immunoglobulin, IgG, and IgM levels at 24 hours, and IgA level at 28 hours, respectively. Serum IgA level reached a minimum at 4 weeks old, IgM level at 5 weeks, total immunoglobulin level at 8 weeks, and IgG level at 10 weeks, respectively. After then those levels had begun to increase, but total protein level was still decreasing at 12 weeks old. The half-lives of IgG, IgM, and IgA were 21.1 days, 4.0 days, and 2.6 days-respectively. In 10 Korean native cows immediately after parturition, serum neutralizing antibody titers specific to BVD, IBR and PI-3 virus were $8.7{\pm}1.5{\log}_2$, $5.7{\pm}1.2{\log}_2$, and $6.8{\pm}1.01{\log}_2$, respectively. And colostral neutralizing antibody titers against BVD, IBR, and PI-3 virus were $10.1{\pm}1.4{\log}_2$, $6.8{\pm}1.3{\log}_2$ and $7.8{\pm}1.7{\log}_2$, respectively. Before suckling the colostrum, SN antibody titers against BVD, IBR, and PI-3 virus were undetectable from all of 9 Korean native calves. Nevertheless SN antibody titer against BVD virus reached a maximum level ($9.2{\pm}0.6{\log}_2$) at 24 hours after birth, that against IBR virus ($6.1{\pm}1.0{\log}_2$) at 20 hours after birth, and that against PI-3 virus ($6.8{\pm}0.9{\log}_2$) at 32 hours after birth, respectively. In 12 weeks old calves, the SN antibodies against BVD and IBR virus were still decreasing, but that against PI-3 virus reached a minimum at 10 weeks, and increased after 12 weeks of age. The half-lives of SN antibodies against BVD, PI-3 and IBR, virus were 16.0 days, 22.6 days, and 25.5 days, respectively.