Comparison of various serological tests on the milk of sheep in relation to the isolation of Brucella melitensis

Abstract

SUMMARY A total of 173 milk ring test (MRT) positive and 356 MRT-negative individuals from 2735 sheep in various stages of lactation were tested by whey complement fixation test (CFT), whey Coombs’ test or antiglobulin test (AGT) and whey agglutination test (AT). These findings were compared with the rate of isolation of Brucella organisms obtained on culture. The whey CFT and whey AGT were more specific and showed a closer relationship to the excretion status of Brucella than whey AT or MRT. Out of 2735 samples of milk 68 MRT-positive and 6 MRT-negative milk samples from aborting sheep were found to be positive on culture. Out of 173 MRT-positive milk samples 58 (33.5 per cent) proved negative culturally and also gave negative results to the other tests. The MRT is less specific than other serological tests for identifying sheep excreting Brucella . However, it is of value as an initial screening test for Brucella infection in milk.