Utilizing leukocyte differentials at arrival to predict death in feedlot calves

Abstract

Although 14.8% of US feedlots (39.3% of US feedlots with capacity of 1000 head or more) treated cattle with an injectable antimicrobial at arrival (USDA 2019), respiratory mortality rates have increased (Vogel et al, 2015). Interventions have been suggested to reduce mortality (Booker et al, 2017), but concerns over antibiotic resistance (Catry et al, 2003) have prompted a need for accurate identification of at-risk animals for more targeted application. As leukocyte differentials have been shown to be predictive of respiratory morbidity (Richeson et al, 2013), the objective of this study was to determine the relationship between leukocyte differentials and risk of respiratory mortality in feedlot cattle.