Effects of an innate immune stimulant on dairy calf respiratory health, Salmonella shedding and nasopharyngeal cytokine gene expression

Bovine respiratory disease (BRD) is a leading cause of morbid­ity and mortality in dairy calves. Alternative treatment strate­gies are needed to reduce antimicrobial use. Innate immune stimulation using toll-like receptor (TLR) agonists has emerged as a strategy to reduce BRD incidence, but the prophylactic ef­fects of this treatment have not been evaluated in pre-weaned dairy calves. Calves that develop enteric disease may be at a higher risk for BRD; however, evidence of direct links between disease processes is limited. Salmonella is an important enteric pathogen in dairy calves, but the impact of Salmonella infection on the risk of BRD development has not been determined. The objectives of this study were to evaluate the effects of an innate immune stimulant on dairy calf respiratory health, Salmonella shedding and cytokine gene expression.