摘要:A total number of 84 female buffaloes, located at Giza province in Egypt during a period extended from 2004 to 2005, were examined for brucellosis using different serological tests. Serological examination revealed prevalence level of 11.9% using RBPT and ARTK followed by TAT (9.5%), CFT (8.3%) and MET (7.1%). Brucella melitensis biovar-3 was isolated from tissue specimens collected from the brucella-positive seroreactive buffaloes during obligatory slaughter. Ten brucella-positive and ten brucella-negative reactors were selected for chromosomal analysis. The frequencies of chromosomal structural aberrations in buffaloes with brucellosis were significantly increased (5.40±0.72) compared with non-infected control group (2.20±0.45). An increase in structural aberrations was observed in the form of fragments, gaps, breaks and deletions. Moreover, a total of 50 dairy cows, collected from a small dairy farm exposed to an outbreak of Bovine Tuberculosis (TB) at Giza province in Egypt, were tested by tuberculin intradermal test using bovine Purified Protein Derivative (PPD) prepared from Mycobacterium bovis ( M. bovis ) and their corresponding milk samples were bacteriologically cultured for M. bovis. A total of 38/50 (76.0%) were positive reactors by single cervical test, while 25/50 (50.0%) were positive by caudal-fold test. Meanwhile, only 24/50 (48.0%) were tested positive by both of the two tests. M. bovis was isolated from milk samples of 19 out of the 50 examined cattle (38.0%). Nine tuberculin positive and nine tuberculin negative cattle were selected for chromosomal analysis. The frequencies of chromosomal abnormalities were also increased significantly in TB infected cattle (5.55±0.52) compared with the control non-infected cows (3.11±0.60). It could be concluded that structural chromosomal aberrations in the form of fragments, gaps, breaks and deletions were significantly increased in buffaloes with brucellosis and dairy cattle with bovine tuberculosis; which could be helpful on genetic control of these diseases.