Efficacy of an Arcanobacterium pyogenes-Fusobacterium necrophorum bacterin-toxoid as an aid in the prevention of liver abscesses in feedlot cattle

Abstract

Two studies were conducted to test the efficacy of a single-dose, bivalent Arcanobacterium pyogenes-Fusobacterium necrophorum bacterin-toxoid to reduce liver abscess prevalence and severity when given to cattle entering a feedlot. In each study, steers (?300/treatment group) were randomized to pens and the pens randomly assigned to treatment groups. Treatment groups included: (1) steers given a high-antigen dose bacterin-toxoid, (2) steers given a lower-antigen dose bacterin-toxoid, (3) steers fed tylosin-medicated feed, (4) control steers fed feed without tylosin, and in Study II only, (5) vaccinated steers fed tylosin-medicated feed. Steers were followed to slaughter and the liver abscesses scored, the USDA carcass and yield grades recorded, and the pen average daily gain and feed conversion calculated. Pen effects were not detected in the analysis of liver abscess prevalence data. A single vaccination with the high-antigen dose bacterin-toxoid reduced the prevalence of liver abscesses 48.4% (16% vaccinates vs. 31% controls, P=0.0001) in Study I, and 37.5% (30% vaccinates vs. 48% controls, P=0.001) in Study II.