The Safety of Vaccinating Beef Replacement Heifers at Weaning Against 18 Antigens

Abstract

Humoral immune responses to vaccination, mean daily gains, morbidity, and mortality were compared in groups of beef replacement heifers from weaning to 4 months after weaning. The only difference in management among groups of heifers was the number and type of vaccines they received. Heifers were vaccinated at weaning (mean age, 205 days) and again 28 days later against 0, 1, 9, 10, 17, or 18 antigens, using commercially available monovalent and multivalent vaccines. Mean daily gain, morbidity, mortality, and serum neutralization antibody titers to bovine respiratory syncytial virus, infectious bovine rhinotracheitis virus, and bovine viral diarrhea virus did not differ among treatment groups. Although the study revealed the safety of vaccinating beef heifers against 18 antigens at weaning, our data emphasized the need for serial vaccination to induce a measurable serum antibody response in animals not exposed previously to the vaccine antigens.