Factors associated with mortality in feedlot cattle: the Bruce County Beef Cattle Project

The design of and the analysis of data from the Bruce County Beef Cattle Project, particularly the field study, are presented and discussed. A major value of the study may lie in its ability to relate laboratory findings to events in the field. The factor most strongly related to mortality was ration, with cattle on hay based rations having a much lower mortality on average than cattle on corn based rations. In general, management activities associated with growing cattle (as opposed to fattening) over the 1st winter were sparing for mortality. Groups of cattle given prophylactic vaccines or drugs within 2 days of arrival tended to experience higher mortality (not statistically higher) than those cattle not receiving those measures, or cattle groups receiving the same prophylactics more than 48 h after arrival. However, these results require validation in the remaining years of the study. Fibrinous pneumonia was the most frequent diagnosis in the calves on post-mortem examination.