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.

A number of changes were noted in the NP microbiota of the cattle from the time they were sampled at the disease-free ranch (d 0) and then after transportation and holding at the feedlot over 14 d. With regard to BRD-associated bacteria, the relative abundance of Mannheimia did not change significantly over time (P > 0.05), although the NP microbiota of one heifer at d 7 was comprised of 30% Mannheimia (Fig. 2a) . Mycoplasma was significantly more relatively abundant at d 14 compared to all other sampling times (P < 0.05; Fig. 2b ). Pasteurella was higher at d 0, although at each of the other three sampling times at least one animal had a relative abundance of at least 10% Pasteurella in their nasopharynx and as a result of this variability this difference was not significant (Fig. 2c) . However, when assessed using LEfSe Pasteurella was found to be enriched at d 0 compared to all other sampling times (Fig. 3) . Six other bacterial genera were identified by LEfSe analysis as being strongly and significantly enriched at one specific sampling time (LDA score [log 10 ] > 4.0; Fig. 3