Comparative efficacy of metaphylaxis with tulathromycin and pentavalent modified-live virus vaccination in high-risk, newly received feedlot cattle
Verónica Muñoz, Kendall L Samuelson, Dexter J Tomczak, Hannah A Seiver, Taylor M Smock, John T Richeson
Abstract
Our objective was to compare metaphylaxis with tulathromycin (META) and vaccination with a pentavalent modified-live virus respiratory vaccine (MLV) in high-risk feedlot calves and their influence on health and growth performance during a 56-d receiving period. Beef bulls (n = 372) and steers (n = 106) were stratified by initial BW (234 ± 1.32 kg), health status, and sex and randomly assigned to treatments arranged in a 2 × 2 factorial: (1) no META or MLV (CON), (2) META administration on d 0 (META), (3) MLV administration on d 0 with revaccination on d 14 (MLV), and (4) META and MLV administration (META+MLV). Interactions and main effects were analyzed within a generalized complete block design using a mixed statistical model with 10 pen replicates per treatment. Body weight and feed refusals were recorded periodically to determine interim and overall (d 0 to 56) performance and feed efficiency. A subset (n = 256) was affixed with a 3-axis accelerometer ear-tag to quantify activity and rumination time. A 7-d postmetaphylactic interval was implemented for META, and bovine respiratory disease cases were determined by treatment-blinded, trained investigators. The META groups had greater ADG from d 0 to 14, from d 14 to 28, and overall (P ≤ 0.01) and BW on d 56 was increased (P < 0.01) 13.52 kg. For each interim period and overall, DMI was increased (P < 0.01) for META but not MLV (P ≥ 0.11). The bovine respiratory disease morbidity rate was less for META (18.5 vs. 51.2%; P < 0.01); however, it was not improved for MLV (P = 0.37). Increased daily rumination time was observed for META (P < 0.05). Health and performance of high-risk feedlot cattle was improved by META but not MLV.