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
DOI:
https://doi.org/10.21423/bovine-vol50no2p154-164Keywords:
bovine, respiratory, BRD morbidity, DNA immunostimulant, delayed viral vaccinationAbstract
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.
