Comparing delayed versus on-arrival administration of a modified live viral vaccine in feedlot cattle

PICO question In auction market calves at high risk of developing bovine respiratory disease (BRD), does delayed (14-30 days) vaccination with a modified live vaccine (MLV) for viral respiratory pathogens versus administration of MLV on-arrival (within 24 hours of arrival) to the feedlot, result in a decreased percentage of calves with BRD morbidity diagnosed based on visual signs and rectal temperature >40 degrees Celsius? Clinical bottom line Category of research question Treatment The number and type of study designs reviewed Two papers were critically reviewed. Both are randomised complete block designs Strength of evidence Weak Outcomes reported Delaying administration of a modified live respiratory vaccine to feedlot cattle may result in lower BRD retreatments Conclusion In feedlot calves, delaying modified live vaccine administration for viral respiratory pathogens may result in lower BRD retreatment rates than cattle receiving the vaccine on arrival to the feedlot. Significant statistical data from one study supported this conclusion while another showed numerically less retreatments in calves vaccinated on arrival versus delayed vaccination.