Belihu, KeJay (PhD)Kassa, Tesfu (Prof)Hailemarian, Mekoonen (PhD)Temesgen Jemberu, Wudu2021-10-292023-11-082021-10-292023-11-082004-06http://etd.aau.edu.et/handle/123456789/28415A longitudinal prospective observational study on calf morbidity and mortality in dairy faons in Dcbre Zeit and its environs was conducted from October II, 2003 to April 8, 2004 with the objective of describ ing incidence of calf morbidity and mortality, investigating potential risk factors related to calf morbidity and mortality and identification ofsomc pathogens associated with calf diarrhea. A total of236 cah'cs, 51 from three large dairy famls and a random sample of 185 calves from market oriented smallholder dairy famls in Ocbre Zeit and its surrounding were included in the study. Each calf was ind ividually identified and regu larly monitored for clinical health problems up to an age of six months. Infomlation on different potential risk factors were collected by personal observation during the regular visit to farms and from questionnaire survey conducted during the study. Fecal samples were also collected from diarrheic calves for laboratory examination to detect entropathogens involved. The overall incidences of crude morbidity and crude mortality found in this study were 61.5% and 18.0%, respectively. Disease conditions/syndromes that were diagnosed in calves included diarrhea, p.neumonia, navel ill, joint ill, septicemic conditions, congenital problems and other miscellaneous cases. The most frequent disease syndrome was calf diarrhea with the incidence of 42.9% followed by pneumonia (4.9%). The incidence of calf diarrhea and crude morbidity were apparently higher in large dairy farms than in the market o riented smallholder farms. However, the mortality was higher in the latter. A total of 20 potential risk factors were investigated for their association with the risk of crude calf morbidity, crude calf mortality and calf diarrhea using Cox's proportional hazard model. Age was the only factor thai was found significantly associated with risk of crude calf mortality (HR= 0.04, P= 0.001). Older calves above three months age were at lower risk of mortality than younger calves under three months of age. When weaned calves were considered, weanin~ age and age at first colostrum feeding were additional risk factors. Among the risk factors examined, those found significantly associated with the incidence of crude morbidity were age of the calves. age at first colostrum ingestion and cleanness of the calf house. Older calves were at lower risk of crude morbidity (HR=O.42, P = 0.001) than younger calves. Higher risk of crude morbidity were observed in calves that ingested their first colostrum meal later than 6 hours of age as compared with those that ingested before 6 V[[] hours (HR = 2.24, P = 0.001). Sim ila rly calves housed at unclean house were at higher risk of crude morbidity than those housed in clean house (HR = 1.75, P = 0.024). Risk factors with sign ifica nt assoc iation to calf diarrhea were age, condition of birth and cleanness of calf house. Older age was again associated with low ri sk of diarrhea as compared with younger age (HR = 0.24, P = 0.000). Calves from prolonged labor or dystocia (HR = 3.01, P = 0.002) and housed at unclean house (HR = 2.34, P = 0.011) were at greater ri sk of diarrhea than those calves from !lonnal delivery and in c lean house, respectively. Based on laboratory examination, Sa/monella and Cryptosporidium were detected from diarrheic calves at ' rate of 2/55(3.6%) and 4/55(7.2%), respectively. The serotypes of Salmonella identified were Salmonella Typhimurium and Salmol/ella Heidelberg both of which were susceptible to commonly used antibiotics. In conclusion, the incidence of calf morbidity and mortality found in this study were high and could affect the productivity of the dairy famls through mainly decreasing the availability of replacement stock. Among the management risk factors investigated, time of first colostrum ingestion and cleanness of the calf house were found very important; incidentally, these two aspects of calf management are easy for observation and carrying out appropriate interventions. Implementation of good calf management in these areas could contribute in the reduction of the -high calf disease problems seen in this study_ Salmollella and Cryptosporidilln/ were found in diarrheic calves and these pathogens in addition to their role in calf diarrhea, are potent zoonotics. Individuals particu larly very young, elderly and immunocompromised, in contact with calves are al a potential risk of infection and therefore, efforts should be mounted to avoid such risks.en-USCalf, Cryptosporidium. dairy fanns, diarrhea, incidence, longitudinal study, morbidity, mortality, ri sk factors, SalmonellaThesis