The AFBI Repository
The Agri-Food and Biosciences Institute Repository collects, preserves, and makes freely available research outputs and related documents created by AFBI researchers, including peer-reviewed articles and conference papers. Where material has already been published it is made available subject to the open-access policies of the original publishers. About AFBI
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Relationship between ambient temperature at sampling and the interferon gamma test result for bovine tuberculosis in cattle
(Elsevier, 2023-05-19) Bisschop, P.I.H.; Frankena, K.; Milne, G. M.; Ford, Tom; McCallan, Lyanne; Young, Fiona; Byrne, Andrew W.
Bovine tuberculosis (bTB) is a disease of significant economic and zoonotic importance, therefore, optimising tests for the identification of Mycobacterium bovis infected cattle is essential. The Interferon Gamma (IFN-γ) Release Assay (IGRA) can diagnose M. bovis infected cattle at an early stage, is easy to perform and can be used alongside skin tests for confirmatory purposes or to increase diagnostic sensitivity. It is known that IGRA performance is sensitive to environmental conditions under which samples are taken and transported. In this study, the association between the ambient temperature on the day of bleeding and the subsequent IGRA result for bTB was quantified using field samples from Northern Ireland (NI). Results of 106,434 IGRA results (2013–2018) were associated with temperature data extracted from weather stations near tested cattle herds. Model dependent variables were the levels of IFN-γ triggered by avian purified protein derivative (PPDa), M. bovis PPD (PPDb), their difference (PPD(b-a)) as well as the final binary outcome (positive or negative for M. bovis infection). IFN-γ levels after both PPDa and PPDb stimulation were lowest at the extremes of the temperature distribution for NI. The highest IGRA positive probability (above 6%) was found on days with moderate maximum temperatures (6–16 °C) or moderate minimum temperatures (4–7 °C). Adjustment for covariates did not lead to major changes in the model estimates. These data suggest that IGRA performance can be affected when samples are taken at high or low temperatures. Whilst it is difficult to exclude physiological factors, the data nonetheless supports the temperature control of samples from bleeding through to laboratory to help mitigate post-collection confounders.
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The impact of BCG strains and repeat vaccinations on immunodiagnostic tests in Eurasian badgers (Meles meles)
(2022-07-09) Courcier, Emily A.; Collins, Shane F.; McCormick, Carl M.; Arnold, Mark E.; Corbett, David; Ford, Tom; McGeown, Clare F.; Barry, Claire; Kirke, Raymond; Menzies, Fraser D.
Bacille Calmette-Guerin (BCG) is a potential tool in the control of Mycobacterium bovis in European badgers (Meles meles). A five year Test and Vaccinate or Remove (TVR) research intervention project commenced in 2014 using two BCG strains (BCG Copenhagen 1331 (Years 1–3/ BadgerBCG) and BCG Sofia SL2222 (Years 4–5). Badgers were recaptured around 9 weeks after the Year 5 vaccination and then again a year later.
The Dual-Path Platform (DPP) Vet TB assay was used to detect serological evidence of M. bovis infection. Of the 48 badgers, 47 had increased Line 1 readings (MPB83 antigen) between the Year 5 vaccination and subsequent recapture. The number of BCG Sofia vaccinations influenced whether a badger tested positive to the recapture DPP VetTB assay Line 1 (p < 0.001) while the number of BadgerBCG vaccinations did not significantly affect recapture Line 1 results (p = 0.59). Line 1 relative light units (RLU) were more pronounced in tests run with sera than whole blood. The results from an in_house MPB83 ELISA results indicated that the WB DPP VetTB assay may not detect lower MPB83 IgG levels as well as the serum DPP VetTB assay. Changes in interferon gamma assay (IFN-γ) results were seen in 2019 with significantly increased CFP-10 and PPDB readings.
Unlike BadgerBCG, BCG Sofia induces an immune response to MPB83 (the immune dominant antigen in M. bovis badger infection) that then affects the use of immunodiagnostic tests. The use of the DPP VetTB assay in recaptured BCG Sofia vaccinated badgers within the same trapping season is precluded and caution should be used in badgers vaccinated with BCG Sofia in previous years. The results suggest that the DPP VetTB assay can be used with confidence in badgers vaccinated with BadgerBCG as a single or repeated doses.
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Measuring the shape of mortality across animals and plants: Alternatives to H entropy metrics reveal hidden type IV survivorship curves and associations with parental care at macro-ecological scales
(John Wiley & Sons Ltd, 2023-05-17) Healy, Kevin; Kelly, Ruth; Carnevale, Angela; Buckley, Yvonne .
The shape of mortality, or how mortality is spread across an organism's life course, is fundamental to a range of biological processes, with attempts to quantify it rooted in ecology, evolution, and demography. One approach to quantify the distribution of mortality over an organism's life is the use of entropy metrics whose values are interpreted within the classical framework of survivorship curves ranging from type I distributions, with mortality concentrated in late life stages, to type III survivorship curves associated with high early stage mortality. However, entropy metrics were originally developed using restricted taxonomic groups and the behavior of entropy metrics over larger scales of variation may make them unsuitable for wider-ranging contemporary comparative studies. Here, we revisit the classic survivorship framework and, using a combination of simulations and comparative analysis of demography data spanning the animal and plant kingdoms, we show that commonly used entropy metrics cannot distinguish between the most extreme survivorship curves, which in turn can mask important macroecological patterns. We show how using H entropy masks a macroecological pattern of how parental care is associated with type I and type II species and for macroecological studies recommend the use of metrics, such as measures of area under the curve. Using frameworks and metrics that capture the full range of variation of survivorship curves will aid in our understanding of the links between the shape of mortality, population dynamics, and life history traits.
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Dietary protected fat and conjugated linoleic acid improves ewe milk fatty acid composition
(2023-05-15) Grigorescu, A.; Balta, I.; Julean, C.; Simiz, E.; Voia, S.; Stef, D.; Alexa, E.; Popescu, I.; Marcu, A.; Pet, I.; Callaway, T.; Corcionivoschi, Nicolae; Ster, L.
The effects of protected fats (Optima 100) and conjugated linoleic acid (Endulac®-CLA) supplementation on sheep milk saturated and unsaturated fatty acid composition were investigated. Sheep were divided into four experimental groups (15 ewes/group) including: i) a control group - basal diet without any nutritional supplements; ii) experimental group 1 - basal diet + 12g/sheep/day of the protected source of fats in the feed; iii) group 2 - 12 g of CLA in the feed; iv) group 3 - 12 g of protected fats and CLA in feed. Sixty milk fatty acids were different in milk from treated fat and CLA-treated sheep compared to the control group. The most biologically important fatty acid constituents of milk were identified as butyric, caproic, caprylic, lauric, myristic, palmitic, stearic, arachidonic, behenic, oleic, and linoleic acid (C4 to C18). Ewes that received protected fat or CLA, or both, displayed an increased concentration of oleic acid compared to the control. Both treatments modified milk lipid quality parameters and increased the polyunsaturated/saturated fatty acids ratio (PUFA/SFA), the polyunsaturation index (PI), and the thrombogenic index (TI). Group 3 had similar milk lipid quality parameters as untreated animals. Compared to the CLA and control groups, milk production in the protected fat treatment was higher in Turcana dairy ewes. The inclusion of protected fats and CLA as dietary supplements in lactating ewes modified the milk fatty acid profile, with a concomitant impact on suckling lamb performance and consumer health.
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Modeling Microplastic Transport in the Marine Environment: Testing Empirical Models of Particle Terminal Sinking Velocity for Irregularly Shaped Particles
(American Chemical Society, 2023-03-22) Coyle, Róisín; Service, Matthew; Witte, Ursula; Hardiman, Gary; McKinley, Jennifer
Microplastic (mP) pollution has been indicated as an area of concern in the marine environment. However, there is no consensus on their potential to cause significant ecological harm, and a comprehensive risk assessment of mP pollution is unattainable due to gaps in our understanding of their transport, uptake, and exchange processes. This research considers drag models that have been proposed to calculate the terminal settling velocity of regularly and irregularly shaped particles to assess their applicability in a mP modeling context. The evaluation indicates three models that predict the settling velocity of mPs to a high precision and suggests that an explicit model is the most appropriate for implementation in a mP transport model. This research demonstrates that the mP settling velocity does not vary significantly over time and depth relevant to the scale of an ocean model and that the terminal settling velocity is independent of the initial particle velocity. These findings contribute toward efforts to simulate the vertical transport of mPs in the ocean, which will improve our understanding of the residence time of mPs in the water column and subsequently their availability for uptake into the marine ecosystem.