Practices and opinions of New Zealand beef cattle farmers towards bovine viral diarrhoea control in relation to real and perceived herd serological status

ABSTRACT

Aims: To investigate the seroprevalence of infection with bovine viral diarrhoea (BVD) virus among 75 beef herds and seroconversion in cattle during early pregnancy, and to determine the practices and opinions of farmers towards BVD control and their association with real and perceived herd serological status.

Methods: Blood samples were collected before mating in 75 beef herds across New Zealand from 15 unvaccinated heifers that had delivered their first calf that season. Serum samples were tested for BVD antibodies using ELISA individually, and after pooling samples for each farm. Animals that were antibody-negative were retested at either pregnancy diagnosis or weaning. Farmers were asked to complete a detailed survey about herd demographics, BVD testing and vaccination practices, and opinions towards national BVD control.

Results: Based on the pooled serum antibody ELISA results, there were 28/75 (37%) negative herds, 15/75 (20%) suspect herds, and 32/75 (43%) positive herds. Of 1,117 animals sampled 729 (65.3%) tested negative for BVD virus antibodies; when retested, 47/589 (8.0%) animals from 13/55 (24%) herds had seroconverted. Among 71 famers providing survey responses 11 (15%) believed their herd was infected with BVD, 24 (34%) were unsure and 36 (51%) did not think their herd was infected. Only 19/71 (18%) farmers had performed any BVD testing within the past 5 years and 50/70 (71%) had not vaccinated any cattle for BVD. Support for national BVD eradication programme was strong in 51/71 (56%) respondents, but the biggest challenge to BVD control was considered to be famer compliance. Compared to farmers who did not think their herd was infected, more farmers who thought BVD was present in their herds had previously tested for BVD, would consider testing all replacement calves, and would support establishing a national BVD database; fewer would consider purchasing BVD tested or vaccinated cattle only.

Conclusions and clinical relevance: Only 15% of the beef farmers in this study believed their herds were infected with BVD virus and few of them had undertaken BVD screening. Nevertheless many were supportive of implementing a national BVD control programme. It is likely that the lack of farmer awareness around BVD and the failure of farmers to recognise the potential impacts in their herds are hindering progress in controlling the disease in New Zealand. There are opportunities for New Zealand veterinarians to be more proactive in helping beef farmers explore BVD management options.

KEYWORDS:

• Bovine viral diarrhoea virus
• beef cattle
• eradication
• farmer behaviour
• epidemiology

Acknowledgments

We are grateful to the 75 beef farmers and 10 veterinary clinics (VetLife, VetEnt, Vet Services Wairarapa, Totally Vets, Eltham District Veterinary Services, Bay of Islands Veterinary Services, Vet Centre Marlborough, West Coast Vets, Wanganui Veterinary Services, and Vet South) who invested considerable time and effort to participate in the studies. We thank Gribbles Laboratory (Emma Sharland and Jo Drake) for their assistance in analysing the laboratory samples and collating the results data. This research programme was sponsored by the Sustainable Farming Fund, AGMARDT, and Massey University. We are also grateful to the national BVD Steering Committee for providing insights into the interpretation of the study findings.

ORCID

M. C. Gates http://orcid.org/0000-0002-7790-1945

Notes

1 https://doi.org/10.1080/00480169.2019.1692735

2 https://doi.org/10.1080/00480169.2019.1692735

3 https://doi.org/10.1080/00480169.2019.1692735