Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: November 3, 1995
Publication Date: N/A
Technical Abstract: Calves (n=104) originated from 4 farms, where half the calves on each were vaccinated with a killed Pasteurella haemolytica serotype 1 product. They were delivered to an order-buyer barn 95 to 98 days later. After 6 days, they were shipped 1600 km by truck to a feedyard, and arrived the next day. At the feedyard, a respiratory tract disease involving 73 calves occurred. On the second day at the feedyard, the vaccinates were revaccinated. At the farm, order buyer barn, and on 4 occasions at the feedyard, nasal secretions and tonsil washes were tested for P. haemolytica, and P. haemolytica IHA serum titers were measured. The incidence of respiratory tract disease was significantly related to the farm of origin, and was inversely proportional to serum titer to P. haemolytica at the farm, but was not influenced by vaccination. Isolations of P. haemolytica serotype 1, however, were reduced by vaccination. The major serotype of P. haemolytica encountered was serotype 1, but serotype 6 was isolated from calves on 1 farm and then from other calves at the feedyard. Vaccination can reduce the frequency of colonization by P. haemolytica serotype 1, which in turn, could reduce losses to pneumonic pasteurellosis.