I. Szasz, T. C. Bryant, K. S. Blood, I. Hardee, J. Jennings, and H. D. Hughes
Applied Animal Science. 2023. 39:273–281
https://doi.org/10.15232/aas.2023-02396
INTRODUCTION: Cattle originating from livestock barns and entering the feedlot are at high risk of contracting bovine respiratory disease (BRD). Vaccination against various viral and bacterial pathogens upon feedlot arrival of cattle is commonly used to mitigate severe disease. Numerous commercial products are available, including modified live virus (MLV) and killed virus vaccines, as well as products containing the bacterial components involved in BRD pathology. Multivalent MLV vaccines are routinely administered in the feedlot, as these products are effective at inducing humoral and cell-mediated immunity, with fewer doses necessary for robust protection compared with killed vaccines. Furthermore, there is strong evidence to suggest that vaccination of beef calves with MLV vaccines in combination with Mannheimia haemolytica (MH) toxoid is effective at reducing BRD morbidity and mortality after weaning.
Intranasal vaccines are an additional tool to enhance protection against BRD by stimulating the mucosal immune response. These vaccines are more akin to natural infection, which occurs when a pathogen breaches the nasal mucosal barrier. Due to maternal antibodies that may interfere with a calf’s immune response to parenteral vaccination, intranasal vaccinations are often administered to young calves. Multiple studies have demonstrated the effectiveness of intranasal vaccination in the face of maternal antibodies following BRD pathogen challenges
However, few studies exist that have compared their efficacy to a MLV vaccine containing MH toxoid in a commercial feedlot setting. Therefore, our research objective was to examine the effects of administering a trivalent intranasal MLV vaccine (Inforce 3, Zoetis, Kalamazoo, MI) in conjunction with 1 of 2 different parenteral MLV respiratory vaccines containing MH toxoid relative to 2 vaccination protocols containing only parenteral MLV respiratory vaccine and MH toxoid.
THE STUDY: Winter-placed heifers (5,240 head; initial BW = 6704 ± 30 pounds) acquired from various auction barns in Texas, Oklahoma, and Missouri were used in this trial. Heifers were allowed 2 to 4 days rest with access to long-stemmed hay, a milled ration, and water, before being randomized among 4 treatments.
- Multivalent parenteral MLV vaccine and a parenteral clostridial bacterin containing MH toxoid
- Multivalent intranasal MLV, parenteral MH toxoid containing MLV bovine diarrhea virus, and parenteral clostridial bacterin
- Multivalent parenteral MLV containing a MH toxoid and parenteral clostridial bacterin
- Multivalent parenteral MLV containing a MH toxoid, multivalent intranasal MLV, and parenteral clostridial bacterin
RESULTS: Morbidity and BRD mortality were similar across treatments. Total death loss was less in heifers that received Treatment 4 versus Treatment 3. Growth performance and carcass traits were unaffected by treatment.
IMPLICATIONS: Intranasal vaccination in lieu of, or administered alongside, a trivalent MLV parenteral respiratory vaccine had no effect on morbidity or feedlot performance, thereby doing no harm. Intranasal vaccination alongside parenteral respiratory vaccine tended to result in lesser BRD mortality. These findings may be useful in designing arrival vaccination protocols for high-risk cattle.