A longitudinal study was conducted from December 2017 to April 2018 in Amibara pastoralrnproduction system. The aims of this study were therefore, to determine passive immunityrnstatus in newborn calves and to identify possible managemental factors that have contributionrnfor the failure of passive transfer of immunity in calves. Each selected calf was individuallyrnneck-tagged and monitored in weekly basis for clinical health problems up to an age of threernmonths. Mean Â± SD IgG concentration of serum samples determined with the bovine radialrnimmunodiffusion assay was 1805.93 Â± 718.68 mg/dL and ranges from 189.132 to 2783.39rnmg/dL. The overall failure of passive transfer of immunity and adequate passive transfer ofrnimmunity status found in this study were 35.11% and 64.89%, respectively. Risk factors suchrnas calve sex, dam parity, birth site, birth condition, mothering instinct and age at firstrncolostrums ingestion were found to have statistically significant effect (P= 0.004 to 0.031). Inrnthe same way morbidity and mortality prevalence were significantly associated with serumrnIgG. Accordingly, 58.82%, 50% and 4.92 % of morbidity was found for complete failure,rnpartial transfer and adequate transfer of passive immunity respectively. As well, 35.29%rn12.5% and 1.64% morbidity was observed for complete failure, partial transfer and adequaterntransfer of passive immunity respectively. The incidence of morbidity and mortality wasrnapparently higher in calves having complete failure and partial passive transfer of immunityrnthan calves having adequate passive transfer. In this study, the highest proportion of failurernof passive transfer of immunity might be due to improper calf and colostrum managementrnpractice and absence of regular care for pregnant cows. Hence improving knowledge ofrnpastoralists concerning calf and colostrum management practice as well caring for pregnantrncows and regular observation of pregnant cows would significantly reduce young stockrnmortality associated with failure of passive transfer of immunity.