Dr. Goshu, GebeyehuMerid, Blen2018-06-282023-11-082018-06-282023-11-082016-06http://etd.aau.edu.et/handle/123456789/4338A cross sectional study was conducted in Bishoftu town from November 2015 to May 2016 with the objectives of investigating major reproductive health problems and their impact on reproductive performance and association with brucellosis in dairy cows. Cross sectional questionnaire survey and observational follow-up were used to determine reproductive parameters and abnormalities. The study was carried out on a total of 519 crossbred dairy cows. The mean age at first service, age at first calving, calving interval, days open, calving to conception interval and number of service preconception were 20.27 months, 29.38 months, 13.42 months, 113.9 days, 130.17 days, and 1.75±1.07 respectively. From the total study animals 30.12% (n= 156) were affected by at least with one reproductive health problem. Among the problems retained fetal membrane, repeat breeder, abortion, anestrus and dystocia were mostly found with their respective prevalence of 10.01%, 7.7%, 7.5%, 3.7% and 3.5%. A total of 291 sera were collected from crossbred dairy cows and Rose Bengal Plate Test was used on sera as a screening test for brucellosis. Rose Bengal Plate Test showed that 15 (5.15%) of the tested samples were screened as positive for brucellosis. Rose Bengal Plate Test positive serum samples were further subjected to Complement Fixation Test for confirmation of brucellosis positivity. From 15 Rose Bengal Plate Test positive sera 12 (4.1%) were also confirmed to be positive by Complement Fixation Test. From the total study animals 39(8.7%) and 52(18.3) were recorded with abortion and retained fetal membrane. Abortion was found significantly associated with sero-positivity of brucellosis in the present study (P<0.05). From the different risk factors studied BCS and parity were significantly associated with reproductive health problems. Also, reproductive trait shows highly significant differences between cows with reproductive abnormalities and those with normal once. This study showed that reproductive disorders highly affected the reproductive performance of dairy cows. Further detailed studies on the major reproductive health disorders in the area should be carried out. Keywords: Bishoftu, Brucellosis, crossbred dairy cattle, reproductive performance, reproductive problemsenBishoftuBrucellosiscrossbred dairy cattlereproductive performancereproductive problemsThesis