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Ramón A. Juste - One of the best experts on this subject based on the ideXlab platform.
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visna maedi virus serology in sheep survey risk factors and implementation of a successful control programme in aragon spain
Veterinary Journal, 2010Co-Authors: Marta M Perez, I Leginagoikoa, Eduardo Berriatua, D De Andres, Ramses Reina, E Biescas, X De Andres, E Salazar, Rosa Bolea, Ramón A. JusteAbstract:Abstract A serological survey of Visna/maedi virus (VMV) infection involving 274,048 sheep from 554 Flocks was undertaken during 2002–2007 in Aragon, North-East Spain. One hundred and two of these Flocks enrolled in a VMV control programme to reduce seroprevalence by selecting replacement lambs from seronegative dams and gradual culling of seropositive sheep. Twenty-five Flocks were also visited to collect flock management and housing data. All study Flocks had seropositive animals and 52.8% of animals tested were seropositive. Among Flocks that joined the control programme 66 adopted the proposed measures and reduced seroprevalence significantly by between 26.1% and 76.9% whereas the remaining 36 Flocks did not apply the measures and seroprevalence significantly increased. Seroprevalence increased with flock size and the number of days the sheep were housed, and decreased with increasing weaning age and shed open area, suggesting a reduced risk of VMV infection in sheep associated with better ventilation. At the end of the period, 24 Flocks were certified as VMV-controlled with a seroprevalence
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border disease virus seroprevalence correlates to antibodies in bulk tank milk and reproductive performance of dairy sheep Flocks
Journal of Dairy Science, 2010Co-Authors: Ana L Garciaperez, Ramón A. Juste, G. Aduriz, Francisco Ruizfons, J F Barandika, Ana HurtadoAbstract:Abstract There is a great need to establish effective tools to control border disease virus (BDV) in European dairy sheep Flocks. Hence, our main aim was to investigate the accuracy of analyzing anti-BDV antibodies in bulk-tank milk (BTM) in detecting the real BDV seroprevalence in dairy sheep Flocks. Furthermore, the relevance of BDV to reproductive performance of dairy sheep Flocks prompted us to search for the association between BDV seroprevalence and reproductive parameters. For these purposes, 34 Flocks were selected based on different percentages of antibody inhibition (AIP) values in BTM as estimated by ELISA. Serum samples from 10 replacement lambs older than 6 mo, 10 ewes 1 to 2 yr old, and 10 ewes >2 yr old were collected and analyzed for the presence of anti-BDV antibodies by ELISA. A negative relationship between BDV AIP in BTM and within-flock seroprevalence was observed. Flocks with a high AIP (>80%) had an average of 2.5% seropositive animals; Flocks with a moderate AIP (46–79%) had 11.4% seropositive animals; and finally, Flocks with an AIP ≤45% showed a high flock seroprevalence (57.2%). Ten out of 34 Flocks showed a high BDV seroprevalence in lambs, suggesting the presence of persistently infected animals in the flock. The observed AIP values in BTM from these likely BDV-infected Flocks were indicative of a high seroprevalence. The analysis of reproductive-parameters data collected from these Flocks showed no differences in fertility or prolificacy in relation to BDV circulation rates. Nonetheless, lamb mortality was significantly greater in Flocks with low-moderate seroprevalence (10–30%), probably as a result of a first-time contact with BDV of previously naive ewes. These findings suggest that testing of BTM samples may be useful in inferring the BDV seroprevalence in a flock.
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Extensive rearing hinders Maedi-Visna Virus (MVV) infection in sheep
Veterinary Research, 2006Co-Authors: I Leginagoikoa, Beatriz Amorena, Juan Jose Badiola, Ramón A. Juste, Damián De Andrés, Jesse Barandika, Luis Luján, Eduardo BerriatuaAbstract:Maedi-Visna Virus (MVV) seroprevalence and its relationship with housing and mode of rearing of replacement ewe-lambs was investigated in 38 non-randomly selected sheep-Flocks in Spain. They included extensive lamb-producing Manchega cross-bred Flocks raised almost permanently at pasture, semi-intensive Latxa dairy Flocks housed 2-8 months/year and intensively raised Assaf dairy Flocks housed most time and at higher stocking density in less ventilated buildings than other Flocks. Most Flocks raised replacement lambs naturally with their dams until weaning and as a separate flock thereafter until lambing at one year of age. Seroprevalence (95% confidence intervals) was 77%, 25% and 5% (4-6) in intensive, semi-intensive and extensive Flocks, respectively and the median (interquartile range) flock-seroprevalence was 82% (66-94) in intensive Flocks, 31% (14-31) in semi-intensive Flocks and 4% (0-7) in extensive Flocks. Seroprevalence was lowest in one year-old sheep and increased to flock levels during the year after introduction into the adult flock in most intensive Flocks and more gradually in other Flocks. Adult flock seroprevalence was associated with housing time but this relationship was not evident within a particular rearing system, indicating that other unknown factors are critical in horizontal MVV-transmission. Low seroprevalence in extensive Flocks further supports previous indications that lactogenic MVV-infection is relatively inefficient and horizontal transmission is necessary to ensure long-term maintenance of MVV and this could explain that MVV has not been reported from countries with mainly extensively reared sheep such as Australia and New Zealand. Moreover, it indicates that MVV-control in extensive and semi-intensive Flocks can be simple and inexpensive.
Ana Hurtado - One of the best experts on this subject based on the ideXlab platform.
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border disease virus seroprevalence correlates to antibodies in bulk tank milk and reproductive performance of dairy sheep Flocks
Journal of Dairy Science, 2010Co-Authors: Ana L Garciaperez, Ramón A. Juste, G. Aduriz, Francisco Ruizfons, J F Barandika, Ana HurtadoAbstract:Abstract There is a great need to establish effective tools to control border disease virus (BDV) in European dairy sheep Flocks. Hence, our main aim was to investigate the accuracy of analyzing anti-BDV antibodies in bulk-tank milk (BTM) in detecting the real BDV seroprevalence in dairy sheep Flocks. Furthermore, the relevance of BDV to reproductive performance of dairy sheep Flocks prompted us to search for the association between BDV seroprevalence and reproductive parameters. For these purposes, 34 Flocks were selected based on different percentages of antibody inhibition (AIP) values in BTM as estimated by ELISA. Serum samples from 10 replacement lambs older than 6 mo, 10 ewes 1 to 2 yr old, and 10 ewes >2 yr old were collected and analyzed for the presence of anti-BDV antibodies by ELISA. A negative relationship between BDV AIP in BTM and within-flock seroprevalence was observed. Flocks with a high AIP (>80%) had an average of 2.5% seropositive animals; Flocks with a moderate AIP (46–79%) had 11.4% seropositive animals; and finally, Flocks with an AIP ≤45% showed a high flock seroprevalence (57.2%). Ten out of 34 Flocks showed a high BDV seroprevalence in lambs, suggesting the presence of persistently infected animals in the flock. The observed AIP values in BTM from these likely BDV-infected Flocks were indicative of a high seroprevalence. The analysis of reproductive-parameters data collected from these Flocks showed no differences in fertility or prolificacy in relation to BDV circulation rates. Nonetheless, lamb mortality was significantly greater in Flocks with low-moderate seroprevalence (10–30%), probably as a result of a first-time contact with BDV of previously naive ewes. These findings suggest that testing of BTM samples may be useful in inferring the BDV seroprevalence in a flock.
Jin Chen - One of the best experts on this subject based on the ideXlab platform.
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the response of birds and mixed species bird Flocks to human modified landscapes in sri lanka and southern india
Forest Ecology and Management, 2014Co-Authors: Eben Goodale, Sarath W Kotagama, T Shankar R Raman, Swati Sidhu, Uromi Manage Goodale, Samuel Parker, Jin ChenAbstract:Abstract While there is no substitute for undisturbed forest, secondary forests and agroforests are increasingly common in tropical areas and may be critical to conservation plans. We compared the diversity and abundance of birds and the characteristics of mixed-species bird Flocks in forests inside protected reserves to “buffer” areas, consisting of degraded forests and non-native timber plantations at reserve boundaries, and to agricultural areas. We monitored a network of 57 transects placed over an altitudinal gradient (90–2180 masl) in Sri Lanka and southern India, collecting 398 complete flock observations and 35,686 observations of birds inside and outside of Flocks over two years. Flocks were rarely found in agricultural areas. However, the density of Flocks in buffer areas was similar to that in forests, although buffer Flocks were smaller in average flock size and differed significantly in composition, as measured by the proportion of species that were classified, from the literature, as forest interior or open-landscape species. While flock composition was distinct between agricultural, buffer and forest areas, the differences in the composition of Flocks was not as great as the differences between the overall communities in these different habitats. Considering buffer transects alone, pine plantations retained fewer forest interior species in Flocks than did forests, and small areas of agriculture and abandoned agriculture attracted open-landscape species. Though clearly not equivalent to protected forests, degraded forests and agroforests in buffer areas still hold some conservation value, with forest species found particularly in mixed-species Flocks in these human-modified habitats.
V M Allen - One of the best experts on this subject based on the ideXlab platform.
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persistent environmental reservoirs on farms as risk factors for campylobacter in commercial poultry
Epidemiology and Infection, 2012Co-Authors: Johanne Ellisiversen, A M Ridley, Victoria K Morris, A Sowa, J A Harris, Robert J Atterbury, N H C Sparks, V M AllenAbstract:Campylobacter is the most common known source of human bacterial enteritis in the developed world and poultry is considered the main source. Broilers often become colonized with Campylobacter during rearing, and then contaminate the farm environment. The objective of this study was to identify Campylobacter-positive environmental reservoirs on farms, as these pose a risk to broiler Flocks becoming colonized with Campylobacter. We considered the temporal aspects of exposure and colonization. A longitudinal study monitored six conventional rearing farms over 2 years. The broiler Flocks, catchers' equipment, vehicles, shed surrounds, shed entrance, other equipment, farm entrance, other animals, puddles, dead birds, mains water and drinkers were systematically sampled 2-4 times per flock. A multivariable generalized estimating equation model was used to assess associations between contaminated environmental sites and colonized broiler Flocks. The associations were adjusted for confounders and other known risk factors. To further assess temporality of contamination, the sequence of contamination of the different environmental sites and the Flocks was established. Contaminated shed entrances and anterooms, contaminated drinkers and shedding of Campylobacter by other animals such as cattle, dogs, wildlife and rodents were significantly associated with positive Flocks. The reservoir of 'other animals' was also the reservoir most commonly positive before the flock became colonized. The other sites usually became contaminated after the flock was colonized.
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campylobacter spp contamination of chicken carcasses during processing in relation to flock colonisation
International Journal of Food Microbiology, 2007Co-Authors: V M Allen, S A Bull, Jel Corry, Gil Domingue, F Jorgensen, J A Frost, R Whyte, A Gonzalez, Nicola C Elviss, T J HumphreyAbstract:The presence and numbers of campylobacters on chicken carcasses from 26 slaughter groups, originating from 22 single-house Flocks and processed in four UK plants, were studied in relation to the level of flock colonisation determined by examining the caecal contents of at least ten birds per group. The prevalence of campylobacters on carcasses from five campylobacter-negative Flocks processed just after other negative Flocks was low ( 8.0 log(10) cfu) than carcasses originating from low prevalence Flocks (average of 2.3 log(10) cfu; range: <1.1 to 4.1 log(10) cfu). There was a reduction in the numbers of campylobacters on carcasses between plucking and chilling in eight of ten fully colonised Flocks. In another eight Flocks, a significant (P<0.001) decrease (0.8 log(10) cfu) in the number of campylobacters on carcasses from just before to after chilling was detected. Campylobacter spp. could be isolated from aerosols, particles and droplets in considerable numbers in the hanging-on, defeathering and evisceration areas but not in the chillers. This was the case even when campylobacters were not isolated from the target flock. Campylobacters on carcasses from two partly colonised Flocks were either the same subtype, as determined by speciation, Multi-Locus Sequence Typing (MLST) and flaA Restricted Fragment Length Polymorphism (RFLP) typing, as those in the fully colonised Flocks processed previously, although not necessarily the most prevalent ones; or were the same subtypes as those found in the caeca of the flock itself. The prevalences of the different campylobacter subtypes found on carcasses from two fully colonised Flocks did not closely reflect those found in the caeca. MLST combined with flaA RFLP provided a good method for ascertaining the relatedness of strains isolated from carcasses and caecal contents. This study showed that carcass contamination is related to the within-flock prevalence of campylobacter colonisation, but that contamination from previously processed Flocks was also significant, especially on carcasses from low prevalence Flocks. Forced dry air cooling of carcasses reduced contamination levels.
J M Rowcliffe - One of the best experts on this subject based on the ideXlab platform.
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competition predation risk and patterns of flock expansion in barnacle geese branta leucopsis
Journal of Zoology, 2003Co-Authors: C Carbone, William A Thompson, L Zadorina, J M RowcliffeAbstract:Changes in the spatial pattern of Flocks of barnacle geese Branta leucopsis were examined in relation to individual behaviour during feeding visits to farm pastures. The Flocks were photographed every 10–20 min, and the shape and location of the flock was determined from a plan view obtained from digitized images of the photographs. Flocks initially maintained a tight formation shortly after arrival, but then tended to expand with increasing residence time. The rate of expansion, however, was significantly greater in large Flocks, with small Flocks showing no consistent pattern. Observed rates of change in flock area were compared with those obtained from a simple model of flock movement in which individuals followed a random walk and moved at a constant speed. In contrast to the observed data, small simulated Flocks (with relatively more edge birds) showed the greatest relative increase in flock area. This discrepancy between the data and the simulation can be explained mechanistically by differences in the behaviour of individuals in Flocks of different sizes. In large Flocks, birds at the leading edge of the flock had faster step rates and travelled further than birds in the centre and at the trailing edge. Rates of movement in small Flocks did not vary with flock position. Levels of vigilance were higher during the first 10 min after arrival, in males, in smaller Flocks and at the edges of Flocks. Thus, upon arrival, Flocks maintain a tight defensive formation with high vigilance, but with increasing residence time, vigilance decreases and larger Flocks expand, suggesting a need for individuals to reduce feeding competition.
