Systematic review and meta-analysis comparing arrival versus delayed vaccination of high-risk beef cattle with 5-way modified-live viral vaccines against BHV-1, BRSV, PI3, and BVD types 1 and 2

Abstract

Bovine respiratory disease (BRD) is the leading cause of morbidity and mortality in North American beef cattle, and thus a major economic and welfare concern of individuals involved in the beef cattle industry. The most common viruses implicated in BRD are Bovine Herpesvirus 1 (BHV-1), Bovine Respiratory Syncytial Virus (BRSV), Parainfluenza 3 (PI3), and Bovine Viral Diarrhea Viruses types 1 and 2 (BVD 1 and 2), and it is common practice to administer vaccines against these viruses to cattle entering feedlots and stocker operations at arrival. However, there have long been concerns that cattle may not mount an optimal immune response when vaccinated at this time. A number of studies have been conducted to evaluate the effects of vaccination timing on morbidity and mortality, but often include other interventions that might confound interpretation of the results. This can make an objective evaluation of the effects of only vaccination timing difficult. It is therefore our goal to provide a systematic review of these studies, and extract relevant data to perform a meta-analysis of vaccine timing on BRD morbidity, retreatment rate, and mortality.