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.

Animal husbandry, experimental design, and sampling of cattle Fourteen Angus × Herford heifers, approximately 8 months of age with an initial body weight of 290 ± 25 kg, were sourced from a research farm that was established in 1984 and free of the following pathogens: the herd was tested annually for bovine viral diarrhea virus, bovine herpes virus-1, Leptospira (serovars Canicola, Pomona, Hardjo, Grippotyphosa, and Copenhageni), Anaplasma phagocytophilum, bluetongue virus, and Brucella abortus, biannually for Mycobacterium avium subspecies paratuberculosis and bovine leukosis virus, and every five years for Mycobacterium bovis. Cattle positive for any of the above disease agents were removed from the herd. None of the cattle used were administered antimicrobials or vaccines prior to or during the study. Calves were weaned 41 d prior to study enrollment (day −41) and were bunk-fed an alfalfa-barley silage mixed diet in pens. On day 0, calves were transported to the feedlot (distance of 20 km).