The nasopharyngeal microbiota of beef cattle before and after transport to a feedlot

Holman, Devin B.; Timsit, Edouard; Amat, Samat; Abbott, D. Wade; Buret, Andre G.; Alexander, Trevor W.

The nasopharyngeal (NP) microbiota of cattle is comprised of a wide range of bacteria, the proportions of which may vary between individual animals and throughout placement in feedlots [1] [2] [3] . Colonization of the nasopharynx begins shortly after birth and the microbiota continues to change as cattle age [4] , although it is typically dominated by members of the Firmicutes, Proteobacteria, and Tenericutes phyla [1] [2] [3] . The relatively abundant genera in the NP microbiota include Corynebacterium, Moraxella, Mycoplasma, Pasteurella, Psychrobacter, and Staphylococcus [1, 3, 5] . Until recently, research regarding the bovine respiratory tract has been focused largely on pathogens. However, with an increasing number of studies showing the importance of the host's microbiota in relation to health [6] , it is important to also evaluate the impact of production practices on the microbiota of livestock. In North America, the majority of beef cattle are finished in feedlots after being purchased from auction markets or directly from farms. The majority of bovine respiratory (BRD) cases also occur within the first weeks of feedlot placement. Therefore, determining how the NP microbiota of cattle responds to introduction to the feedlot environment is important for understanding why cattle are most susceptible to BRD during this period.