Blood and whey serological tests (RBPT, TAT, Riv.n as well as milk ring test
were preformed on individual samples obtained from 84 dairy cows for diagnosis of
bovine brucellosis. Also, samples were taken from colostrum and milk to evaluate the
effect of brucellosis on immunoglobulin concentrations using ELISA. In addition, milk
samples were used for isolation and identification of brucella organisms. Results revealed that the incidence of brucellosis using blood serum were
21.42, 25.0 and 20.23% with RBPT, TAT and Riv.T, respectively. Meanwhile, in whey
the corresponding figures were 11.90, 10.71 and 13.09%. The milk ring test revealed
that the incidence of brucellosis was 13.09 %. Brucellosis caused significant increases in all immunoglobulin fractions in
mammary secretions, especially IgA in colostrum as well as IgG and IgA and total Igs
in milk of infected cows, as compared to that of the normal control cows. While, IgM
was obviously lower in milk of brucella positive cows. Only two isolates of brucella melitensis biovar 3 were isolated from 21
positive TAT reactors milk samples. It was concluded that for proper rapid screening of brucellosis, MRT should
not be performed alone.