Effects of delayed respiratory viral vaccine and/or inclusion of an immunostimulant on feedlot health, performance, and carcass merits of auction-market derived feeder heifers

Abstract

A total of 5,179 high-risk heifer calves were used to define the potential benefits of delaying the on-arrival respiratory viral vaccine (Pyramid® 5, Boehringer Ingelheim Vetmedica, Inc., St. Joseph, M0] for 30 d with and without the addition of a DNA immunostimulant (Zelnate® DNA Immunostimulant, Bayer Animal Health, Shawnee Mission, KS) at feedlot entry on health, performance, and carcass characteristics. The products were evaluated in a 2 x 2 factorial, randomized complete-block design comparing the following: delayed vaccine (DP), on-arrival vaccine (AP), delayed vaccine plus immunostimulant (DPZ), and on-arrival vaccine plus immunostimulant (APZ) amongst 60 total pens of heifers (15 pens/treatment). Pen-level linear mixed models, including a random effect for allocation block (source), were used for all statistical analyses. There was no P x Z interaction (P > 0.35) for any outcome. At 60 DOF, reimplant (116 d), and close-out, delaying the viral vaccine decreased (P < 0.05) the percent of calves treated twice for bovine respiratory disease (BRD). The inclusion of immunostimulant reduced (P <0.05) BRD mortality and overall mortality at both 60 and 116 DOF. Additionally, the reduction (P = 0.04) in overall mortality and the tendency to lessen BRD mortality (P = 0.06) was maintained through close-out for cattle administered the immunostimulant. No differences in final gain performance, dry matter intake or feed conversion were observed among treatments. There was a tendency for heifers to have heavier finished body weights (P = 0.08) and HCW (P = 0.07) when vaccinated on arrival. No differences in carcass quality or yield grade categories were evident. In conclusion, delaying the viral vaccine and including the immunostimulant both appeared to improve cattle health by significantly reducing BRD retreatment risk and overall mortality, respectively.

Comparing delayed versus on-arrival administration of a modified live viral vaccine in feedlot cattle

“…Each summary of the studies we evaluated includes a list of the current manufacturer, brand name, and the viruses included in the MLV respiratory vaccine administered. It is important to note that different vaccines and protocols were tested in the two studies we evaluated (Hagenmaier et al, 2018;and Rogers et al, 2016). Therefore, although both studies provide evidence for our question related to delayed vs on-arrival MLV use, they do not provide consistent evidence in terms of products used.…”

“…However, it also introduces variability into the results of this Knowledge Summary as much of the prior health data and origin data are unknown. Another limitation is that the two studies considered in this Knowledge Summary only explored delayed vaccination in heifers, therefore the impact of gender, if any, cannot be evaluated (Hagenmaier et al, 2018;and Rogers et al, 2016). Finally, the fact that both studies had less animals per pen than would typically be found in a commercial setting could influence the external validity of the results as respiratory disease dynamics are often different when the pen size is smaller.…”

“…However, they did not answer the specifics of the presented question and thus were excluded from the review. The two studies reviewed in this summary are randomised controlled trials*, which produce the strongest evidence of experimental studies (Hagenmaier et al, 2018;and Rogers et al, 2016). Though each of these studies evaluated a large number of cattle, the experimental unit for each study was pen which means the sample sizes for detecting differences in each study are relatively small.…”

“…For our question, the strength of evidence is weak overall because the reviewed papers are small experimental studies, and each have limitations to answering the presented question (Hagenmaier et al, 2018;and Rogers et al, 2016). Within the details of each study, we have provided a list of limitations either identified directly or limitations that result from a lack of detail in the manuscript.…”