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

## TL;DR

Delaying a modified live vaccine in high-risk calves may reduce the need for retreatments for bovine respiratory disease compared to vaccinating immediately upon arrival.

## Contribution

This study compares delayed versus immediate vaccination timing in feedlot calves for BRD outcomes.

## Key findings

- Delaying MLV administration may reduce BRD retreatment rates in feedlot calves.
- One study found significant statistical support for reduced retreatments with delayed vaccination.
- Another study showed numerically fewer retreatments with on-arrival vaccination.

## Abstract

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