2019 CRWAD

2019 Conference of Research Workers in Animal Diseases (CRWAD)

Organic dairy producers’ perspectives concerning vaccination and antimicrobial use

J. Pempek, C. Brock, K. Weaver, D. Jackson-Smith, L. DaCosta, and G. Habing

Vaccination is critical to herd health and food security, yet negative perceptions of vaccine safety may limit their use. Our prior survey showed that organic dairy producers vaccinate calves less frequently and rarely use antimicrobials, even for severe cases of disease. Organic producers are obligated to initiate antimicrobial therapy for severely ill animals, but little information exists on how producers make this decision in the face of stringent rules. The goal of this study was to use semi-structured interviews to characterize the influencers and barriers of vaccine and antimicrobial use among organic dairy producers. Twenty-one organic dairy producers in Ohio were individually interviewed to explore the decision-making processes on vaccination, treatment patterns for common bacterial diseases, and the veterinarian’s role in such decisions. Qualitative answers to semi-structured questions were systematically analyzed to assess key concepts using NVivoTM software. Sixty-two percent (13/21) of producers reported using vaccines. Attitudes surrounding vaccine hesitancy or refusal were complex, and concerns regarding safety or side effects and inconvenience were cited by 83% (5/6) and 100% (6/6) of producers, respectively. Any use of antimicrobials was reported by 43% (9/21) of producers, most of whom reported isolated treatment events and grappled with a case definition to initiate therapy. Beyond removal from the organic herd, barriers to antimicrobial use included the inconvenience and financial disincentive of managing the treated animal through withdrawal. Reported local veterinary involvement was sparse; producers often relied on veterinary advisors associated with their dairy cooperative for recommendations. Overall, many organic dairy producers reported using vaccines. Still, findings highlight opportunity to address negative perceptions surrounding vaccine safety or side effects. Protocols that clarify case definitions that warrant antimicrobial therapy are needed through a more profound, mutually-beneficial relationship with a veterinarian.

Prevalence of Non-typhoidal Salmonella in veal calf production

S. Locke1, N. Aulik2, D. Sockett2, R. Meyer2, J. Pempek1, R. Portillo-Gonzalez1, G. Habing1

1The Ohio State University College of Veterinary Medicine, Department of Veterinary Preventive Medicine, Columbus, Ohio, 2Wisconsin Veterinary Diagnostic Laboratory, Madison, Wisconsin.

The inclusion of peripheral lymph node (LN) tissue in ground beef contributes to foodborne transmission of non-typhoidal Salmonella (NTS) as LN can harbor NTS. However, the source and timing of LN infections in cattle are unclear. Previously, our lab recovered multi-drug resistant NTS serovars in the LN tissues of 20-week old veal calves just prior to slaughter despite low on-farm prevalence in fecal and environmental samples, which suggests that other exposures were responsible for the NTS LN carriage. Therefore, the objective of this prospective cohort study was to assess prevalence and strain types of NTS at additional points in veal calf production. We hypothesized that NTS strains present in LN samples would be indistinguishable from NTS strains present in the trailer or holding pen environments, indicating potential areas of exposure. Nine cohorts of roughly 82 calves per cohort were enrolled between November 2018 and July 2019. Environmental swabs were taken in the source barn (n=6), livestock trailer used to haul calves to the harvest facility (n=8), and harvest facility holding pens (n=8). Trailer and pen samples were collected before and after calf entry. We collected mesenteric LNs from 35 calves per cohort and pooled prefemoral LNs from 25 calves per cohort. Sample culture, enrichment, and analysis was conducted by Wisconsin Veterinary Diagnostic Laboratory. In general, environments were highly contaminated with NTS in which NTS was isolated from 70.8% (51/72) of trailer and 91.7% (66/72) of holding pen samples. NTS was confirmed in 30.8% (91/295) of mesenteric LNs and in the prefemoral LNs of three cohorts. NTS prevalence in LNs was variable between cohorts and ranged from 0% to 80%. For two cohorts, matching serotypes (Agona, Typhimurium) were recovered from trailer and pen environments and the LNs of calves. Whole genome sequencing will be used to determine the relatedness of serogroup B strains, pinpointing areas of exposure, information critical for the development of effective preharvest Salmonella prevention methods.