Date of Graduation

5-2012

Document Type

Thesis

Degree Name

Master of Science in Animal Science (MS)

Degree Level

Graduate

Department

Animal Science

Advisor

Paul A. Beck

Committee Member

Elizabeth B. Kegley

Second Committee Member

David L. Kreider

Third Committee Member

Jeremy G. Powell

Fourth Committee Member

Shane Gadberry

Abstract

Stress alters the immune system and vaccination during this time may reduce vaccine response; whereas, growth implants may shift metabolism to enhance tissue deposition in exchange for energy required for immune response during bovine respiratory disease (BRD) challenge. This study was conducted to determine the effects of pentavalent respiratory vaccination timing with or without a hormonal growth implant on arrival (d 0) on health, performance, complete blood count, and vaccine response in high&ndashrisk, newly received stocker calves during a 42&ndashd receiving period. Crossbred bull and steer calves (n = 385) were weighed (initial BW = 202 ± 4.1 kg), stratified by castrate status on arrival, and assigned randomly to 1 of 4 treatments arranged in a 2 × 2 factorial: 1) arrival (d 0) vaccination, with implant (AVACIMP), 2) arrival vaccination, without implant (AVAC), 3) delayed (d 14) vaccination, with implant (DVACIMP), 4) delayed vaccination, without implant (DVAC). The percentage of calves treated for BRD once, twice, or thrice was 80, 50 and 20%, respectively, but did not differ (P ≥ 0.12) among treatments. Likewise, days to initial BRD treatment was not affected by vaccine timing (P = 0.66) or implant (P = 0.24). Overall ADG (d 0 to 42) did not differ due to vaccination timing (P = 0.53) or implant (P = 0.64). White blood cell count was not different (P ≥ 0.76) among treatments, but exhibited a cubic response over time (P = 0.01), with counts increasing from d 0 to d 28 prior to leveling off at the end of receiving (d 42). The neutrophil:lymphocyte ratio decreased (linear, P ≤ 0.0001) throughout receiving. Bovine viral diarrhea virus type 1a antibody concentrations were greater (P = 0.02) for calves vaccinated on arrival and increased over time for both vaccine treatments (P = 0.01). Results indicate a hormonal growth implant administered on&ndasharrival to high&ndashrisk stocker calves did not increase ADG. Morbidity rate was high but was not impacted by vaccine timing or implant. Vaccination on arrival increased bovine viral diarrhea virus type 1a antibody concentrations throughout receiving.

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