Temporal trends in bulk milk antibodies to Salmonella, Neospora caninum, and Leptospira interrogans serovar hardjo in Irish dairy herds

Abstract

Bulk milk samples were collected from 309 Irish dairy herds at four time points during 2009 and tested for antibodies to Salmonella spp., N. caninum and L. hardjo, three abortifacient agents in Irish dairy herds. Of the 309 study herds, 49% vaccinated for Salmonella and 76% vaccinated for L. hardjo. In unvaccinated herds, the overall prevalence of antibody positive herds was 49% for Salmonella, 19% for N. caninum and 86% for L.hardjo. There was no association between both testing positive for and incidence of caninum or L. hardjo. There was, however, a tendency towards a higher incidence of Salmonella in regions of Ireland with higher cattle densities.

Herd-level prevalence of selected endemic infectious diseases of dairy cows in Great Britain

“…This is most likely due to the effect of environmental factors (i.e., higher rainfall in these regions in 2014; MetOffice, 2014) as well as differences in grazing practices (i.e., access to pasture and duration of grazing; Sekiya et al, 2013). In relation to N. caninum, seasonal variation in the prevalence has been previously reported (O'Doherty et al, 2013). Due to limited financial resources in our study, only a single testing was carried out, which could have resulted in some positive herds being missed, especially on farms tested during early stages of the lactation (O'Doherty et al, 2013).…”

“…The estimated prevalence values of most of the studied pathogens broadly agree with those reported from other countries, where these pathogens are considered endemic, suggesting similar pathogen dynamics [BVDV and BHV-1 (Kampa et al., 2004;Sayers et al, 2015;Fernandes et al, 2016), MAP (Muskens et al, 2000;van Schaik et al, 2003), C. burnetii (van Engelen et al, 2014), Salmonella spp., and Leptospira Hardjo (Habing et al, 2012;O'Doherty et al, 2013). Higher-prevalence estimates of F. hepatica (Cringoli et al, 2002;Olsen et al, 2015) and N. caninum infections were estimated in our study compared with some other countries (Sanderson et al, 2000;O'Doherty et al, 2013).Bulk milk samples were used to assess herd status based on the presence of specific antibodies or antigen. Our prevalence estimates are therefore herd-level estimates and they are subject to misclassification bias as a result of imperfect Se or Sp of the tests applied at the level of the herd.…”

Questionnaire identifying management practices surrounding calving on spring-calving dairy farms and their associations with herd size and herd expansion

“…These included the total number of dairy cows on the farm for each of the 3 years, mean herd parity and average herd age Calving management on spring-calving dairy farms (recorded for each cow at calving), percentage of heifers in the lactating herd, length of calving season, mean annual herd milk production (calculated from individual cow milk recordings; liters), milk fat and protein (kg), herd somatic cell count (SCC), herd economic breeding index values (EBI), and the predominant breed of cow in the herd. Calving season length refers to duration (weeks) for which ⩾85% cows are calving between January and June (O'Doherty et al, 2013). The EBI value is a single figure profit index used to identify the most profitable bulls and cows for breeding dairy herd replacements .…”

Management practices as risk factors for the presence of bulk milk antibodies to Salmonella, Neospora caninum and Leptospira interrogans serovar hardjo in Irish dairy herds

“…Selection of herds for use in this study has been previously described in detail by O'Doherty et al (2013). Briefly, 312 herds which were members of HerdPlus ® , a breeding information decision support tool for farmers co-ordinated by the Irish Cattle Breeding Federation (ICBF), volunteered to participate in the study.…”

“…An investigation of the temporal trends in bulk milk antibody levels to Salmonella, Neospora caninum (N. caninum) and Leptospira interrogans serovar hardjo (L. hardjo) in Irish dairy herds was completed in 2009 (O'Doherty et al, 2013). This study documented herd-level seroprevalences of 49%, 19% and 86% for Salmonella, N. caninum and L. hardjo, respectively, with no association found to exist between the prevalence of these pathogens with one another.…”