The influence of feedlot management on an outbreak of bovine respiratory disease.

Epidemic curves, odds ratios and chisquare were used to investigate an epidemic of respiratory disease in a pen of feedlot cattle. The cattle were divided into four groups by an eartag number received at processing. Data for each group were collected from feedlot records describing purchase, transportation and processing histories, daily feeding methods, daily pen movements, daily diagnoses, treatment and mortality rates. These data were used to describe the effects of market origin and feeding management on the levels and distribution of respiratory disease.The three groups of cattle purchased from auction markets and started on high levels of grain in their rations were determined to be 6.3 times (P<0.0005) more likely to be treated for any disease, 4.9 times (P<0.0005) more likely to be treated for respiratory disease, 12.7 times (P<0.0025) more likely to die, and 6.7 times (P<0.0471) more likely to die with respiratory disease than the group made up primarily of farm-assembled heifers and started on a 10% grain ration with time for adjustment to grain.