RESUMO

INTRODUCTION: A feedlot is an intensive farming system for finishing livestock. Bovine respiratory disease (BRD) is a cause of morbidity and mortality in beef cattle, especially in feedlots. METHODOLOGY: This study investigated the morbidity and mortality of BRD in a beef cattle feedlot in southeastern Brazil using: clinical diagnoses, therapy, morbidity, and mortality. Pulmonary fragments were collected from five steers, on feed from 3-32 days, with lesions of pneumonia for identification of BRD infectious agents PCR. RESULTS: 188,862 steers were on feed and morbidity was 7.05% (13,315/188,862), mortality 0.64% (1,214/188,862). The causes of morbidity were: BRD (6.13%), lameness (0.29%), trauma (0.21%), clostridiosis (0.13%) and polioencephalomalacia, PEM (0.12%). The causes of mortality were: BRD (0.21%), trauma (0.17%), and clostridiosis (0.13%). When all sick cattle were considered (n=13,315), BRD (86.9%) was the principal cause of morbidity, followed by lameness (4.13%), trauma (3.05%), and clostridiosis (1.82%). The cost of BRD-associated cattle mortality and morbidity was estimated at $14,334.00/10,000 and $16,315.40/10,000 respectively. It was projected that the economic effects due to BRD-associated morbidity in Brazil were $6.31 million/annum, while losses due to mortality were $5.54 million, resulting in an annual loss of $11.85 million. Coinfections in cattle with pneumonia due to Mannheimia haemolytica and Pasteurella multocida were identified in 4/5 steers tested. CONCLUSIONS: This is the first longitudinal study that investigated the incidence of BRD in feedlot cattle from Brazil, and the results herein described indicate that BRD contributed significantly to the development of mortality and morbidity of cattle on feed.