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Marsh M.K.,University of York | McLeod S.R.,Australian Department of Primary Industries and Fisheries | Hutchings M.R.,Disease Systems | White P.C.L.,University of York
Wildlife Research | Year: 2011

Context Social structure of group-living animals has important implications for processes such as gene flow, information transfer, resource utilisation, and disease spread. However, due to the difficulties associated with measuring relationships among wild animals and deriving meaningful estimates of social structure from these interactions, quantifying sociality of evasive species can be challenging. Aims Our aim was to quantify the pattern of social interactions among free-ranging European wild rabbits (Oryctolagus cuniculus) in a temperate region of Australia. Methods We used proximity logging devices to collect data on the dyadic interactions among two populations of rabbits. We then applied recently developed social structure and network analytical techniques to infer estimates of sociality and contact networks from recorded interactions. Key results We found large heterogeneities in the strength of association indices and network centrality measures within but not between populations. Network analytical techniques revealed clustering of rabbits into distinct social groups. Conclusions Most associations within social groups were strong and highly stable over time whereas interactions between groups were rare and transient, indicating low levels of inter-group mixing. Despite the apparent differences in habitat quality between sites, the network characteristics were extremely similar between the two populations. Implications Our results highlight the importance of heterogeneities in individual behaviour in determining the dynamics of directly transmitted diseases at the population level. © 2011 CSIRO. Source

Houdijk J.G.M.,Disease Systems
Small Ruminant Research | Year: 2012

This review addresses the question whether host resistance to gastrointestinal nematodes is sensitive to metabolizable protein (MP) or metabolizable energy (ME) scarcity. Several ruminant studies have addressed this question, and with additional data from monogastric models and post-rumen infusion methodologies, there is convincing evidence that host resistance to gastrointestinal nematodes is sensitive to MP scarcity and not (moderate) ME scarcity. A possible evolutionary reason for this variation has been evoked. Attempts to dissect the role of MP and ME scarcity on resistance to parasites in ruminants is hampered by the modifying role of the rumen, as ME supplementation usually results in confounding MP supply, arising from increased microbial protein synthesis. The latter contributes less to intestinal MP than by-pass protein, and has an amino acid composition that is less compatible with that of immune proteins, compared to MP arising from animal protein sources. Thus, the largest benefits from supplementation on host resistance to gastrointestinal nematodes are expected to arise from protein-rich foods rather than from energy-rich foods. In addition, dietary protein quality in terms of level of by-pass protein and amino acid composition of resulting intestinal MP are important factors to consider in non-chemical parasite control strategies in small ruminant production systems. © 2011 Elsevier B.V. Source

Hardstaff J.L.,University of York | Marion G.,Biomathematics and Statistics Scotland | Hutchings M.R.,Disease Systems | White P.C.L.,University of York
Research in Veterinary Science | Year: 2014

Tuberculosis (TB) caused by infection with Mycobacterium bovis (. M. bovis) and other closely related members of the M. tuberculosis complex (MTC) infects many domestic and wildlife species across Europe. Transmission from wildlife species to cattle complicates the control of disease in cattle. By determining the level of TB hazard for which a given wildlife species is responsible, the potential for transmission to the cattle population can be evaluated. We undertook a quantitative review of TB hazard across Europe on a country-by-country basis for cattle and five widely-distributed wildlife species. Cattle posed the greatest current and potential TB hazard other cattle for the majority of countries in Europe. Wild boar posed the greatest hazard of all the wildlife species, indicating that wild boar have the greatest ability to transmit the disease to cattle. The most common host systems for TB hazards in Europe are the cattle-deer-wild boar ones. The cattle-roe deer-wild boar system is found in 10 countries, and the cattle-red deer-wild boar system is found in five countries. The dominance of cattle with respect to the hazards in many regions confirms that intensive surveillance of cattle for TB should play an important role in any TB control programme. The significant contribution that wildlife can make to the TB hazard to cattle is also of concern, given current population and distribution increases of some susceptible wildlife species, especially wild boar and deer, and the paucity of wildlife TB surveillance programmes. © 2013 Elsevier Ltd. Source

Valiakos G.,University of Thessaly | Valiakos G.,Center for Research and Technology Hellas | Papaspyropoulos K.,University of Thessaly | Papaspyropoulos K.,Research Division | And 20 more authors.
PLoS ONE | Year: 2014

West Nile Virus (WNV) is the causative agent of a vector-borne, zoonotic disease with a worldwide distribution. Recent expansion and introduction of WNV into new areas, including southern Europe, has been associated with severe disease in humans and equids, and has increased concerns regarding the need to prevent and control future WNV outbreaks. Since 2010, 524 confirmed human cases of the disease have been reported in Greece with greater than 10% mortality. Infected mosquitoes, wild birds, equids, and chickens have been detected and associated with human disease. The aim of our study was to establish a monitoring system with wild birds and reported human cases data using Geographical Information System (GIS). Potential distribution of WNV was modelled by combining wild bird serological surveillance data with environmental factors (e.g. elevation, slope, land use, vegetation density, temperature, precipitation indices, and population density). Local factors including areas of low altitude and proximity to water were important predictors of appearance of both human and wild bird cases (Odds Ratio = 1,001 95%CI = 0,723-1,386). Using GIS analysis, the identified risk factors were applied across Greece identifying the northern part of Greece (Macedonia, Thrace) western Greece and a number of Greek islands as being at highest risk of future outbreaks. The results of the analysis were evaluated and confirmed using the 161 reported human cases of the 2012 outbreak predicting correctly (Odds = 130/31 = 4,194 95%CI = 2,841-6,189) and more areas were identified for potential dispersion in the following years. Our approach verified that WNV risk can be modelled in a fast cost-effective way indicating high risk areas where prevention measures should be implemented in order to reduce the disease incidence. © 2014 Valiakos et al. Source

Ricci P.,Future Farming Systems | Ricci P.,Instituto Nacional de Tecnologia Agropecuaria | Chagunda M.G.G.,Future Farming Systems | Rooke J.,Future Farming Systems | And 5 more authors.
Journal of Animal Science | Year: 2014

The laser methane detector (LMD) has been proposed as a method to characterize enteric methane (CH4) emissions from animals in a natural environment. To validate LMD use, its CH4 outputs (LMD-CH4), were compared against CH4 measured with respiration chambers (chamber-CH4). The LMD was used to measure CH4 concentration (μL/L) in the exhaled air of 24 lactating ewes and 72 finishing steers. In ewes, LMD was used on 1 d for each ewe, for 2-min periods at 5 hourly observation periods (P1 to P5, respectively) after feeding. In steers fed either low- or high-concentrate diets, LMD was used once daily for a 4-min period for 3 d. The week after LMD-CH4 measurement, ewes or steers entered respiration chambers to quantify daily CH4 output (g/d). The LMD outputs consisted of periodic events of high CH4 concentrations superimposed on a background of oscillating lower CH4 concentrations. The high CH4 events were attributed to eructation and the lower background CH4 to respiration. After fitting a double normal distribution to the data set, a threshold of 99% of probability of the lower distribution was used to separate respiration from eructation events. The correlation between mean LMDCH4 and chamber-CH4 was not high, and only improved correlations were observed after data were separated in 2 levels. In ewes, a model with LMD and DMI (adjusted R2 = 0.92) improved the relationship between DMI and chamber-CH4 alone (adjusted R2 = 0.79) and between LMD and chamber-CH4 alone (adjusted R2 = 0.86). In both experiments, chamber-CH4 was best explained by models with length of eructation events (time) and maximum values of CH4 concentration during respiration events (μL/L; P < 0.01). Correlation between methods differed between observation periods, indicating the best results of the LMD were observed from 3 to 5 h after feeding. Given the short time and ease of use of LMD, there is potential for its commercial application and fieldbased studies. Although good indicators of quantity of CH4 were obtained with respiration and eructation CH4, the method needed to separate the data into high and low levels of CH4 was not simple to apply in practice. Further assessment of the LMD should be performed in relation to animal feeding behavior and physiology to validate assumptions of eructation and respiration levels, and other sources of variation should be tested (i.e., micrometeorology) to better investigate its potential application for CH4 testing in outdoor conditions. © 2014 American Society of Animal Science. All rights reserved. Source

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