Prevalence of Mycoplasma bovis in backgrounding and stocker cattle operations

Objective - To characterize the prevalence of Mycoplasma bovis infection in backgrounding and stocker cattle operations and compare bacteriologic culture with PCB assay for detection of M bovis. Design - Prospective descriptive study. Animals - 432 calves, 3 to 9 months old, from 9 operations. Procedures - 2 nasal swab specimens were collected from each calf. Swab specimens were evaluated via bacteriologic culture and PCR assay for organisms of the class Mollicutes and M bovis. Culture results were considered negative if no growth occurred within 21 days. Positive results were indicated by characteristic colony formation with PCR assay confirmation. Deoxyribonucleic acid was extracted from 1 swab specimen for direct PCB assay for Mollicutes and M bovis. Results - Of 432 calves, 374 (87%) had positive results for Mollicutes via PCR assay and 63 (15%) via culture. Seven (2%) calves had positive results for M bovis via PCB assay and 10 (2%) via culture. Prevalence of Mollicutes at the farm level ranged from 54% to 100% via PCR assay and from 0% to 59% via culture. Prevalence of M bovis at the farm level ranged from 0% to 4% via PCB assay and from 0% to 6% via culture. Calves that shed M bovis were significantly more likely to have a fever than were calves that did not shed M bovis. Conclusions and Clinical Relevance - M bovis was detected at a low level in recently purchased backgrounded and stocker calves in Georgia. Although slightly more infected calves were detected via culture and PCR assay together, PCR assay appeared to accurately identify M bovis at the farm level.