Clinical response of feeder calves under direct IBR and BVD virus challenge

A comparison of two vaccines and negative control

Abstract

The effects of 2 virus vaccines on morbidity and mortality in autumn weaned feeder calves was evaluated. Treatment I cattle received a multivalent vaccine consisting of chemically altered IBR and PI3, viruses, a modified live BRSV, an inactivated BVDV, and a bacterin containing 5 Leptospira interrogans serovars (canicola, grippotyphosa, hardjo, icterohaemorrhagiae, and pomona (Cattle Master 4 + L5TM)). Treatment II cattle received an all killed virus IBTBFD-PI3-BRSV and a bacterin containing 5 L. interrogans serovars. Treatment III cattle were not vaccinated. All animals were subjected to direct aerosol challenge with virulent IBR and BVD virus 30 days after booster vaccination. The non-vaccinated group was included to provide a measure of the severity of challenge, and to serve as a basis of comparison for the vaccinated groups. All cattle were sero-negative for IBR and BVD prior to initiation of the study. The 2 vaccinated groups (Treatment I and II) received primary and booster inoculations prior to virus challenge. The control group (Treatment III) remained sero-negative to IBR and BVD until challenge. Treatment I calves experienced a morbidity rate of 8% and no mortality. Treatment II calves experienced a morbidity and mortality of 13%. Morbidity and mortality in Treatment III calves were 100% and 58% respectively. A statistically significant reduction in morbidity and mortality was demonstrated in vaccinated calves versus non-vaccinated calves. A significant reduction in morbidity and mortality was also demonstrated in the calves that received the chemically altered virus, MLV, and killed virus combination vaccine as compared to the calves that received the all killed virus vaccine. The authors conclude this study supports the use of combination virus vaccines for the control of IBR and BVD induced respiratory disease in autumn weaned calves.