Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/20/2010
Publication Date: 2/6/2011
Citation: Runyan, C.A., Herring, A.D., Ridpath, J.F., Cabaniss, M.S., Muntean, C.T., Sawyer, J.E. 2011. Health measures in beef steers of known genetic background following BVDV challenge [abstract]. American Society for Animal Science Southern Section Meeting, February 6-9, 2011, Orlando, Florida. Abstract No. 4. Interpretive Summary:
Technical Abstract: Angus-sired steers (n = 95) born in the spring of 2008 produced from TAMU McGregor Genomics Project cows were evaluated for health measures following challenge to BVD virus. Steers were not vaccinated for BRD prior to trial initiation, and were verified to be BVD-free. Prior to BVDV challenge, steers were assigned to BRD vaccination treatments (VACTRT) of killed (KV; n = 29), modified-live (MLV; n = 34) or non-vaccinated (NON; n = 31) with sires and genomics cow families stratified across VACTRT. On d-56, KV steers were administered their first injection; on d-35, KV steers were administered a booster injection and MLV steers were administered their only injection. On d 0, all steers were given an intranasal challenge with BVDV strain CA0401186a (Type 1b) from the National Animal Disease Center. Serum neutralizing IgG titers for IBR, BVD Type1 (BVD1) and BVD Type2 (BVD2) were evaluated on d-56, -35, -0, -14, -28, and -42. Weights and rectal temps were collected on these days as well as d 1, 3, 7, and 10. Rectal temperature (RTEMP) and IgG titers (log base 2 transformed) were analyzed through mixed model procedures as repeated measures with VACTRT, day, VACTRT x day, sire, and VACTRT x sire in the models. Differences in RTEMP were observed (P < 0.05) due to VACTRT, day, VACTRT x day, and sire. Peak RTEMP was observed on d 7 (39.6 +/= 0.05 deg C). At d 7 MLV steers had lower (P < 0.05) RTEMP (39.2) than KV or NON steers (both 39.8). Differences in BVD1 and BVD2 titers showed similar patterns with VACTRT, day, VACTRT x day, and sire accounting for variation; a VACTRT x sire interaction was present for BVD1 (P = 0.08) that was not present for BVD2 (P = 0.50). IBR titers showed large differences due to VACTRT, day and VACTRT x day, but not sire or VACTRT x sire. KV steers had higher (P < 0.05) titers for IBR, BVD1, and BVD2 than MLV steers, which in turn were higher (P < 0.05) than titers of NON steers. On day 0, KV and MLV steers had equal BVD1 titers, but KV steers had higher BVD2 than MLV steers. There were large titer differences among individuals in all VACTRT, and it appears substantial genetic variation exists in response to BRD vaccines.