Iraqi Journal of Veterinary Sciences

Abstract

The study was conducted to investigate bovine tuberculosis in three dairy cows stations using comparative tuberculin test
(bovine and avian) and bacterial isolation. Sixty five, 3950 and 1185 cows in the first, second and third station, respectively,
were Subjected for comparative tuberculin. All animals in the first station showed negative results for the tuberculin test,
whereas the percentage of positive tuberculin cows in the second and third stations were 0.4% and 16.64%, respectively.
Accordingly, cows with positive tuberculin from the second and third stations were discarded and samples were collected from
these animal pre and post slaughtering for bacterial isolation. Nine months after the first investigation the rest of cows (59,
3934 and 968) in the three stations were subjected for tuberculin test and bacterial isolation as previously, all cows in the first
station remained negative for tuberculin test. On the other hand, tuberculin positive cows decreased to 0.31% and 8.26% in the
second and third stations, respectively. Cultural examination of the 184 samples collected from positive tuberculin cows
revealed that, a total of 113 (61.41%) mycobacterial strains were isolated from 92.30% of the lungs (24 of 26), 84.60% of the
lymph nodes (22 of 26), 84.00% of the livers (21 of 25), 55.00% of the spleens (11 of 20), 54.05% of the milk samples (20 0f
37) and 30.00% of the nasal swabs (15 of 50). Biochemically, of the 113 strains, 103 were identified as M. bovis , 2 as Runyon III mycobacterium, 4 as Runyon IV mycobacterium and 4 as Runyon IV saprophytic mycobacterium. Results of this work
confirmed the importance of applying the program of test and elimination of infected animals for the control of bovine
tuberculosis.