Associations between paratuberculosis ELISA results and test-day records of cows enrolled in the Irish Johne's Disease Control Program

peer-reviewedThe effect of the Mycobacterium avium ssp. paratuberculosis (MAP) ELISA status on test-day milk performance of cows from Irish herds enrolled in the pilot national voluntary Johne's disease control program during 2013 to 2015 was estimated. A data set comprising 92,854 cows and 592,623 complete test-day records distributed across 1,700 herds was used in this study. The resulting ELISA outcome (negative, inconclusive, and positive) of each cow within each year of the program was used to allocate the cow into different scenarios representing the MAP status. At MAPscenario1, all cows testing ELISA nonnegative (i.e., inconclusive and positive) were assigned a MAP-positive status; at MAPscenario2 only cows testing ELISA-positive were assigned a MAP-positive status; at MAPscenario3 only cows testing ELISA nonnegative (inconclusive or positive) and gathered exclusively from herds where at least 2 further ELISA nonnegative (inconclusive or positive) cows were found were assigned a MAP-positive status; at MAPscenario4 only cows testing ELISA-positive that were gathered exclusively from herds where at least 2 further ELISA-positive cows were found were assigned a MAP-positive status. Milk outputs based on test-day records were standardized for fat and protein contents (SMY) and the effect of MAP ELISA status on the SMY was estimated by a linear mixed effects model structure. The SMY mean difference recorded at test day between cows with a MAP-positive status and those with a MAP-negative status within MAPscenario1 was estimated at −0.182 kg/test day; the mean difference was −0.297 kg/test day for MAPscenario2; for MAPscenario3 mean difference between MAP-positive status and MAP test-negative cows was −0.209 kg/test day, and for MAPscenario4, the difference was −0.326 kg/test day.This study was carried out as part of the ICONMAP (Improved Control of Mycobacterium avium ssp. paratuberculosis) multidisciplinary research program, funded by the Research Stimulus Fund 2011, administered by the Irish Department of Agriculture, Food and the Marine

The Northern Ireland Control Programmes for Infectious Cattle Diseases Not Regulated by the EU

Publication history: Accepted - 26 July 2021; Published online - 26 August 2021.The disease control programmes for Bovine Viral Diarrhoea (BVD), Infectious Bovine Rhinotracheitis (IBR), Johne's Disease (JD), Leptospirosis and Neosporosis are described including the approved diagnostic tools, diagnostic quality systems, and the role of vaccination (where appropriate). This paper describes the control programmes within NI, the challenges relating them, as well as assessing their impact and effectiveness, taking into consideration the quality of data available and number of herds participating. With the NI agricultural industry experiencing increasing financial pressures and post Brexit changes, the necessity of working to maximise the performance of bovine disease control programmes at the individual farm level as well as at the regional level is increasingly important. The programmes described fall into two categories with two distinct aims. Two managed by Animal Health & Welfare NI (AHWNI), the BVD eradication and JD Dairy Control programmes seek to eradicate or control infection at the regional level. A further 5 programmes, covering BVD, JD, IBR, Leptospirosis and Neosporosis, are managed by the Agri-Food and Biosciences Institute (AFBI) and focus on facilitating eradication or control at the individual herd level. These latter programmes conform to the Cattle Health Certification Standards (UK) (CHeCS) which is a UK self-regulatory body set up to ensure consistency between different disease control schemes across herds. The largest of all the programmes described is the AHWNI BVD Eradication Programme which has led to significant reductions in infection incidence. Compliance with it has been high with more than 97% of all cattle alive at the end of 2020 having a BVD test status. The rolling annual incidence of BVD virus positive calves has fallen by 56% since the start of the compulsory programme in 2016. This decrease has occurred largely through industry initiatives to deal with BVD positives, including the voluntary culling of persistently infected (PI) animals by herd owners, a voluntary abattoir ban on the slaughter of BVD virus (BVDv) positive animals, and the inclusion of retention of a BVDv positive animal as a non-conformance in the industry-run Farm Quality Assurance Scheme.This article is based upon work from COST Action Standardizing output-based surveillance to control non-regulated diseases of cattle in the European Union (SOUND control) CA17110 supported by COST (European Cooperation in Science and Technology)

Is There a Relationship Between Bovine Tuberculosis (bTB) Herd Breakdown Risk and Mycobacterium avium subsp. paratuberculosis Status? An Investigation in bTB Chronically and Non-chronically Infected Herds

Publication history: Accepted - 23 January 2019; Published - 14 February 2019.Background: Bovine tuberculosis (bTB; Mycobacterium bovis) remains a significant problem in a number of countries, and is often found where M. avium subsp. paratuberculosis (MAP) is also present. In the United Kingdom, bTB has been difficult to eradicate despite long-term efforts. Co-infection has been proposed as one partial mechanism thwarting eradication. Methods: A retrospective case-control study of 4,500 cattle herds in Northern Ireland, where serological testing of cattle for MAP, was undertaken (2004–2015). Blood samples were ELISA tested for MAP; infection of M. bovis was identified in herds by the comparative tuberculin test (CTT) and through post-mortem evidence of infection. Case-herds were those experiencing a confirmed bTB breakdown; control-herds were not experiencing a breakdown episode at the time of MAP testing. A second model included additional testing data of feces samples (culture and PCR results) to better inform herd MAP status. Multi-level hierarchical models were developed, controlling for selected confounders. A sensitivity analysis of the effect of MAP sample numbers per event and the prior timing of tuberculin-testing was undertaken. Results: 45.2% (n = 250) of case observations and 36.0% (3,480) of control observations were positive to MAP by ELISA (45.8% and 36.4% when including ancillary fecal testing, respectively). Controlling for known confounders, the adjusted odds ratio (aOR) for this association was 1.339 (95%CI:1.085–1.652; including ancillary data aOR:1.356;95%CI:1.099–1.673). The size-effect of the association increased with the increasing number of samples per event used to assign herd MAP status (aOR:1.883 at >2 samples, to aOR:3.863 at >10 samples), however the estimated CI increased as N decreased. 41.7% of observations from chronic herds were MAP serology-positive and 32.2% from bTB free herds were MAP positive (aOR: 1.170; 95%ci: 0.481–2.849). Discussion: Cattle herds experiencing a bTB breakdown were associated with increased risk of having a positive MAP status. Chronic herds tended to exhibit higher risk of a positive MAP status than bTB free herds, however there was less support for this association when controlling for repeated measures and confounding. MAP co-infection may be playing a role in the success of bTB eradiation schemes, however further studies are required to understand the mechanisms and to definitively establish causation

Quantification of the effect of in-utero events on lifetime resilience in dairy cows

Currently, the dairy industry is facing many challenges that could affect its sustainability, including climate change and public perception of the industry. As a result, interest is increasing in the concept of identifying resilient animals, those with a long productive lifespan, good reproductive performance and milk yield. There is much evidence that events in utero, i.e., the Developmental Origins of Health and Disease (DOHaD), alter life-course health of offspring and we hypothesized that these could alter resilience in calves, where resilience is identified using lifetime data. The aim of this study was to quantify lifetime resilience scores (LRS) using an existing scoring system based on longevity with secondary corrections for age at first calving and calving interval and to quantify the effects of in-utero events on the LRS using 2 data sets. The first was a large data set of cattle in 83 farms in Great Britain born from 2006 to 2015 and the second was a smaller, more granular data set of cattle born between 2003 and 2015 in the Langhill research herd at Scotland's Rural College. Events during dam's pregnancy included health events (lameness, mastitis, use of an antibiotic or anti-inflammatory medication), the impact of heat stress as measured by temperature-humidity index and perturbations in milk yield and quality (somatic cell count, percentage fat, percentage protein and fat:protein ratio). Daughters born to dams that experienced higher temperature-humidity indexes while they were in-utero during the first and third trimesters of pregnancy had lower LRS. Daughter LRS scores were also lower where milk yields or median fat percentages in the first trimester were low, and when milk yields were high in the third trimester. Dam LRS was positively associated with LRS of their offspring, however, as parity of the dam increased, LRS of their calves decreased. Similarly, in the Langhill herd, dams of a higher parity produced calves with lower LRS. Additionally, dams which recorded a high max locomotion score in the third trimester of pregnancy were negatively associated with lower calf LRS in the Langhill herd. Our results suggest that events that occur during pregnancy have lifelong consequences for the calf's lifetime performance. However, experience of higher temperature-humidity indexes, higher dam LRS scores and mothers in higher parities explained a relatively small proportion of variation in offspring LRS, which suggests that other factors play a substantial role in determining calf LRS scores. While 'big data' can contain a considerable amount of noise, similar findings between the 2 data sets indicate it is likely these findings are real.</p

Pestivirus Apparent Prevalence in Sheep and Goats in Northern Ireland: A Serological Survey

Publication history: Accepted - 30 October 2020; Published - 12 January 2021.Background: Bovine viral diarrhoea virus (BVDV) and border disease virus (BDV) can cause significant health problems in ruminants and economic impacts for farmers. The aim of this study was to evaluate pestivirus exposure in Northern Ireland sheep and goat flocks, and to compare findings with a previous study from the region. Methods: Up to 20 animals were sampled from 188 sheep and 9 goat flocks (n = 3,418 animals; 3,372 sheep and 46 goats) for pestivirus antibodies. Differentiation of the causative agent in positive samples was inferred using serum neutralisation. Abortion samples from 177 ovine cases were tested by BVDV reverse-transcription polymerase chain reaction and antigen ELISA. Results: Apparent animal and flock (one antibody positive animal within a flock) prevalence was 1.7% and 17.3%, respectively, a statistically significant drop in apparent prevalence since a survey in 1999. 52.6% of samples testing positive had higher antibody titres to BVDV than to BDV. Of the ovine abortion samples, only one positive foetal fluid sample was detected by ELISA. Conclusion: The present study found that, since 1999, there has been a decrease in apparent animal and flock prevalence of 3.7 and 12.8 percentage points respectively, suggesting pestivirus prevalence has decreased across Northern Ireland between 1999 and 2018.This research was funded by the Department of Agriculture, Environment and Rural Affairs