Comparative effectiveness of intranasal and parenteral vaccines for prevention of bovine respiratory disease in feedlot heifers

Our objective was to examine the effects on bovine respiratory disease (BRD) when administering a trivalent intranasal modified live virus (MLV) vaccine in conjunction with 1 of 2 different parenteral MLV respiratory vaccines containing Mannheimia haemolytica (MH) toxoid relative to 2 vaccination protocols containing only parenteral MLV respiratory vaccine and MH toxoid. Heifers (BW = 304 ± 5.7 kg; n = 5,240) procured from auction barns were assigned to 1 of 4 treatments at arrival processing: (1) concomitant administration of multivalent parenteral MLV vaccine and a parenteral clostridial bacterin containing MH toxoid (BOV); (2) concomitant administration of multivalent intranasal MLV, parenteral MH toxoid containing MLV bovine diarrhea virus, and parenteral clostridial bacterin (IF3); (3) concomitant administration of multivalent parenteral MLV containing a MH toxoid and parenteral clostridial bacterin (PYR); and (4) concomitant administration of multivalent parenteral MLV containing a MH toxoid, multivalent intranasal MLV, and parenteral clostridial bacterin (COMB). Morbidity and BRD mortalitiy were similar across treatments. Total death loss was less in heifers that received COMB versus PYR, and BRD death loss tended to be less in COMB heifers. Growth performance and carcass traits were unaffected by treatment. 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.