BRD’s Impact on Performance and Carcass Traits Using Treatment Records and Lung Lesion Scores
The objective of this study was to investigate the effects of bovine respiratory disease (BRD) complex on economically important production traits with the use of health records in combination with lung lesion scores obtained at harvest. Records from 5,976 animals were used in this study from cattle that were managed in Midwestern feedlots. Average daily gain for three different feeding periods (acclimation, on-test and overall test) along with final body weight was evaluated as performance measures. Hot carcass weight, longissimus muscle area, subcutaneous fat cover and marbling score were collected at harvest. All calves were monitored by experienced feedlot personnel and treated according to the specific health protocol of each feedlot.
Incidence of BRD was observed at a rate of 8.2%, and lung lesions at harvest were present in 61.9% of cattle from a sub population (n = 1,665).
From this group of cattle, the overall incidence of BRD, defined as incidence of BRD and/or cattle with lung lesions at the packing plant, was 64.4%.
Incidence of BRD in the feedlot decreased average daily gain during both the acclimation period (0.82 lb) and the overall test period (0.15 lb).
Incidence of BRD also had significant effects on HCW and marbling score with reduction of 18 lb and 0.13, respectively, in treated cattle.
The adverse effects on production traits tended to increase as the number of treatments increased. Potential decrease in performance and carcass merit observed in this study were associated with a decline of $23.23, $30.15 and $54.01 in carcass value when comparing cattle never treated to cattle treated once, twice or three or more times, respectively. The presence of lung lesions did not have a significant effect on any of the traits; however, there was an association between the presence of active bronchial lymph nodes and lower productivity of feedlot cattle.
Source: Iowa State University Extension