Effects of vaccination prior to transit and administration of florfenicol at time of arrival in a feedlot on the health of transported calves and detection of<i>Mannheimia haemolytica</i>in nasal secretions

Abstract

Administration of florfenicol at time of arrival decreased the incidence of MH organisms in the nasopharynx and delayed the onset of RTD. Prophylactic use of suitable antibiotics is likely to reduce the incidence of acute RTD in calves for several days after arrival at feedyards, which is the period when they are most susceptible to infectious organisms.