RESPIRATORY VACCINATION STRATEGIES TO ENHANCE MUCOSAL AND SYSTEMIC IMMUNE RESPONSES IN BEEF CALVES

Prevention of bovine respiratory disease (BRD) in the U. S. beef industry is typically approached using vaccination strategies upon arrival to the feedlot, since vaccination at the cow-calf sector has a low adoption rate. Four experiments were conducted to explore novel vaccination routes and viral-bacterial combination vaccines in cattle. Experiments 1 and 2 evaluated novel mucosal vaccination routes and experiments 3 and 4 compared two combination viral-bacterial respiratory vaccines. In experiment 1, 42 crossbred beef steers were administered 1 of 5 treatments, consisting of three titrated oral doses of pentavalent modified live viral respiratory vaccine, a label administration of injectible pentavalent vaccine, or saline administered orally as a negative control treatment. Results indicated no immunological benefit to oral vaccination of calves with a pentavalent respiratory vaccine administered orally. In experiment 2, 30 healthy beef heifer calves were administered a commercially available intranasal trivalent modified live respiratory vaccine, a pentavalent respiratory vaccine labeled for parenteral administration but administered intranasally, or saline administered intranasally. Serum and mucosal antibodies were undetectable in cattle treated with intranasal administration of a vaccine labeled for parenteral vaccine, which could be caused by interference of the adjuvant in the vaccine. Experiments 3 and 4 observed the effects of two different combination viral-bacterial respiratory vaccines containing Mannheimia haemolytica components compared to an unvaccinated negative control group. In experiment 3, cattle on either combination vaccine treatment elicited greater leukotoxin antibody responses on d 7, 14, and 28 post-vaccination compared to control calves, suggesting that the two vaccines are comparable in protection against leukotoxin produced by Mannheimia haemolytica bacteria. The acute phase response and performace were evaluated following the same comparison in experiment 4. Cattle receiving Pyramid 5 + Presponse SQ had greater concentrations of haptoglobin compared to control cattle, with Bovi-Shield Gold 5 One Shot treatment being intermediate, which could suggest a greater inflammatory response stimulated by the Presponse vaccine. No differences in performance were observed. Further research investigating these vaccination strategies could lead to the implementation of products at the cow-calf sector that reduce BRD prevalence and minimize morbidity and mortality in the feedlot attributable to BRD.