Effectiveness of vaccination of feedlot cattle with bovine respiratory syncytial virus (BRSV)

Abstract

In 1984, 96 calves of approximately 500 pounds body weight were kept in a feedlot in 6 pens (16 calves/pen). 48 of the calves in 3 pens were vaccinated with an attenuated BRSV vaccine. At the start of the trial 62% calves in the vaccination treatment group and 50% in the non-vaccinated group were seropositive to BRSV and at the end of the trial 92% of calves in both groups were seropositive. In 1985 the experiment was repeated with a similar group of calves. 50% and 23% calves respectively were seropositive at the start of the trial and 92% and 75% were seropositive respectively at the end of the trial. The average daily weight gain of the vaccinated cattle was 12% greater than the non-vaccinated cattle during the 32 day trial in 1984 and 74% greater during the 28 day trial in 1985. In both trials the pounds of feed consumed per pound of weight gained was higher in the non-vaccinated cattle. The incidence of cattle with respiratory diseases requiring treatment was 33% in the vaccinated groups in both years and 44% and 46% in the non-vaccinated groups in 1984 and 1985.