Characterization of bacterial populations recovered from the teat canals of lactating dairy and beef cattle by 16S rRNA gene sequence analysis

Bovine mastitis is of major concern to the dairy industry worldwide. The bovine teat canal is the primary route through which pathogens enter the mammary gland. The microflora of the teat canals of dairy and beef cattle was investigated by analysis of 16S rRNA gene sequences. The goal was to examine the global difference between dairy cattle, which are sanitized on a regular basis, and beef cattle, which receive little sanitary management. A diverse population of 16S rRNA gene sequences was recovered from both the dairy and the beef herd samples, with diversity higher in the beef sample. Analysis revealed the presence of 90 operational taxonomic units (OTUs) among 156 sequences, with 45 OTUs in the dairy sample and 53 OTUs in the beef sample. Only eight OTUs were common to both samples. Members of the classes Clostridia and Bacilli dominated both samples, followed by Actinobacteria and Proteobacteria. The dairy sample contained a cluster (20/80 clones) of Staphylococcaceae members, seven of which were identifiable as coagulase-negative Staphylococcus species. The beef sample was dominated by members of the genus Clostridia, many of which have not been previously cultured. The results suggest that the microorganisms present in the bovine teat canal are more diverse than previously described.