The Effect of intranasal IBR-PI3 vaccination of feeder cattle on arrival at a feedlot compared with vaccination at the start of an outbreak of acute respiratory tract disease

Abstract

A group of 6-9month old Hereford heifers were vaccinated intranasally with modified live IBR-PI3 vaccine on arrival at a feedlot. Of these, 35% subsequently required treatment for acute respiratory disease, with clinical symptoms including depression, anorexia, increased respiration rate, lacrimation, excess nasal discharge and rectal temperature of 104 deg F. Of the unvaccinated controls, 55% needed treatment, and of contact controls, 57% developed clinical symptoms. In another group of animals, vaccination was not given until respiratory disease occurred. Of these, 68% of the vaccinated animals and 50% of the unvaccinated controls required treatment for acute respiratory tract disease. From the results it is concluded that giving IBR vaccine before possible exposure to the virus is preferable to giving it when infection has already occurred, as vaccination of a sick animal is an additional stress.