Search Results

Abstract

Objective—To determine whether vaccine virus can be detected by use of reverse transcriptase (RT)-PCR assays for pooled and individual skin samples obtained from cattle after vaccination with a commercially available modified-live bovine viral diarrhea virus (BVDV) vaccine.

Animals—12 BVDV-seropositive steer calves and 7 BVDV-seronegative (antibody titer < 1:4) heifers; all cattle were free of persistent infection with BVDV.

Procedures—2 experiments were conducted. Cattle were vaccinated on day 0 with a commercially available modified-live BVDV vaccine. Skin samples were collected on days 0, 3 to 14, 16, and 18 for virus detection by use of RT-PCR assay on individual and pooled samples. In addition, blood samples and nasal swab specimens were collected for virus isolation.

Results—All cattle, regardless of serologic status, had negative results for BVDV as determined by use of RT-PCR assay of individual and pooled skin samples. Virus was detected via virus isolation in serum or the buffy coat in 5 of 7 heifers that were seronegative when vaccinated.

Conclusions and Clinical Relevance—These findings indicated that it would be unlikely to detect BVDV vaccine virus in skin by use of RT-PCR assay of individual or pooled skin samples obtained from cattle after vaccination with a commercially available modified-live BVDV vaccine. Veterinarians and producers should be confident that positive test results for BVDV on skin samples would not likely be caused by the vaccination virus after administration of a modified-live virus vaccine.

Abstract

Objective—To evaluate the effects of a voluntary regional bovine viral diarrhea virus (BVDV) control project implemented in the Upper Peninsula of Michigan.

Design—Longitudinal study.

Sample—294 cattle producers and 11,917 cattle from the Upper Peninsula.

Procedures—Producer participation was assessed to determine the effectiveness of the project's promotional and educational campaigns. Participating herds were screened for cattle persistently infected (PI) with BVDV by real-time reverse transcriptase PCR assay on ear notch specimens from all newborn calves and cattle that did not calve (bulls and young stock) during the year of enrollment. Responses to a survey administered to producers 4 years after project initiation were evaluated to assess the project's effect on BVDV management practices implemented by producers.

Results—294 of 495 (59%) known cattle producers in the Upper Peninsula participated in the project, and 11,917 cattle from 232 herds were tested for BVDV, of which 22 (0.18%) cattle from 9 (3.9%) herds were identified as PI with BVDV and euthanized or slaughtered. Of 140 survey respondents, 85 (61%) indicated they would test all new herd additions for BVDV, 83 (59%) would quarantine new herd additions for 30 days before introducing them to the main herd, and 81 (58%) would use the fact that their herd was free of cattle PI with BVDV for marketing purposes.

Conclusions and Clinical Relevance—Results indicated that the project enhanced producer knowledge about BVDV and led to changes in producer behavior regarding BVDV management. Stakeholder engagement was as critical to project success as was increased BVDV knowledge.

Abstract

OBJECTIVE To determine whether feeding a direct-fed microbial (DFM) to dairy calves would reduce total and antimicrobial-resistant coliform counts in feces and affect average daily gain (ADG).

ANIMALS 21 preweaned Holstein heifer calves.

PROCEDURES The study had a randomized complete block design. Within each block, 3 consecutively born calves were randomly assigned to 1 of 3 treatment groups within 24 hours after birth (day 0). Calves were fed the DFM at 1.0 g (DFM1; n = 7) or 0.5 g (DFM2; 7) twice daily or no DFM (control; 7) from days 0 through 29. A fecal sample was collected from each calf daily on days 0 through 3 and then every other day through day 29. Fecal samples were cultured, and mean numbers of total coliforms and coliforms resistant to ampicillin, ceftiofur, and tetracycline were compared among the 3 treatment groups. Calves were weighed on days 0 and 29 to calculate ADG.

RESULTS Mean total fecal coliform counts did not differ significantly among the 3 treatment groups. Mean ceftiofur-resistant and tetracycline-resistant coliform counts for the control group were significantly lower, compared with those for the DFM1 and DFM2 groups. Mean ADG did not differ significantly between the DFM1 and DFM2 groups; however, the mean ADG for all calves fed the DFM was 0.15 kg less than that for control calves.

CONCLUSION AND CLINICAL RELEVANCE Results suggested that the DFM fed to the preweaned calves of this study did not reduce total or antimicrobial-resistant coliform counts in feces.