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Flocks
Kinds of Flocks Selected AbstractsOvine alpha-amylase genes: isolation, linkage mapping and association analysis with milk traitsANIMAL GENETICS, Issue 4 2004J. H. Calvo Summary On the basis of comparisons between cattle and sheep genome mapping information the ovine , - amylase gene was examined as a possible genetic marker for milk traits in sheep. The objective of the present study was to isolate, map and determine whether this gene is a candidate gene for milk traits. DNA fragments (832 and 2360 bp) corresponding to two different AMY genes were isolated, and one SNP in intron 3 and one GTG deletion in exon 3 of the 2360 bp DNA fragment were found. The 2360 bp ovine AMY DNA fragment was located on chromosome 1 by linkage mapping using the International Mapping Flock. No association was found between estimated breeding values for milk yield, protein and fat contents and AMY genotypes in a daughter design comprising 13 Manchega families with an average of 29 daughters (12,62) per sire. [source] Potential Effects of Passenger Pigeon Flocks on the Structure and Composition of Presettlement Forests of Eastern North AmericaCONSERVATION BIOLOGY, Issue 6 2003JOSHUA W. ELLSWORTH We suggest that the activities of roosting and nesting Passenger Pigeons caused widespread, frequent disturbances in presettlement eastern forests through tree limb and stem breakage and nutrient deposition from pigeon excrement. We suspect that the deposition of fine fuels resulting from such disturbances may have influenced fire intensity and frequency in presettlement forests. Further, we propose that consumption of vast quantities of acorns by pigeons during the spring breeding season may partially explain the dominance of white oak (Quercus alba) throughout much of the presettlement north-central hardwoods region. Consequently, the pigeon's extinction may have facilitated the increase and expansion of northern red oak (Quercus rubra) during the twentieth century. Although it is difficult to accurately quantify how physical and chemical disturbances and mast consumption by Passenger Pigeon flocks affected forest ecology, we suspect they shaped landscape structure and species composition in eastern forests prior to the twentieth century. We believe their impact should be accounted for in estimates of the range of natural variability of conditions in eastern hardwood forests. Resumen:,Consideramos los posibles efectos que pudieron haber tenido parvadas de Palomas Migratorias (Ectopistes migratorius) sobre el régimen de perturbación y la composición de especies de bosques en Norte América oriental antes de la colonización. Sugerimos que las actividades de perchado y anidación de las palomas causaron perturbaciones frecuentes y extensas en los bosques orientales antes de la colonización por medio de la ruptura de ramas y tallos de árboles y la deposición de nutrientes del excremento de las palomas. Sospechamos que la deposición de combustibles resultantes de tales perturbaciones pudo haber influido en la intensidad y frecuencia de incendios forestales. Más aún, proponemos que el consumo de grandes cantidades de bellotas por las palomas en la primavera puede parcialmente explicar la dominancia de roble blanco (Quercus alba) en muchos de los bosques nor-orientales. En consecuencia, la extinción de la paloma pudo haber facilitado el incremento y expansión del roble rojo (Quercus rubra) durante el siglo veinte. Aunque es difícil cuantificar con precisión como las perturbaciones físicas y químicas y el consumo masivo por parvadas de palomas migratorias afectaron a la ecología forestal, sospechamos que modelaron la estructura del paisaje y la composición de especies en los bosques orientales antes del siglo veinte. Creemos que su impacto debería ser considerado cuando se hacen estimaciones del rango de variabilidad natural de las condiciones en bosques orientales de maderas duras. [source] Age-Related Microhabitat Segregation in Willow Tit Parus montanus Winter FlocksETHOLOGY, Issue 11 2000Lluís Brotons It is expected that through flexibility in behaviour, flock living birds respond to the asymmetries in resource access derived from dominance relationships. We analysed the microhabitat use of willow tits in winter flocks and assessed possible factors which shape habitat segregation between adults and juveniles in different temperature regimes. When foraging in mild conditions (ambient temperature >,0°C), flocks split up into subgroups with adults foraging in inner parts of trees more often than juveniles. However, no differences were recorded in the vertical position occupied in trees. In harsh conditions (< , 4°C), flocks re-united and juveniles further moved to outer parts of trees, increasing horizontal segregation between age classes. In mild conditions, vigilance behaviour was not related to the position of birds in trees, but in harsh conditions, scanning frequency was higher in outer parts of trees only for adults. In mild weather, juvenile position in trees was associated with body size and mass. The foraging microhabitat segregation detected in harsh conditions fits the age-related hoarding distribution previously described in the same population. This supports the hypothesis that hoarded food is important in determining future foraging habitat use. Adult preference and intraspecific competition for safer or richer inner parts of trees as foraging sites during harsh conditions seems to determine the habitat segregation between adults and juveniles. Furthermore, we suggest that in mild weather, when foraging in the absence of adults, juveniles balance the costs of using a potentially dangerous microhabitat with the benefits of building energetically cheap and large food reserves through hoarding. The expected patterns of microhabitat segregation may differ in parids, depending on whether predation risk or other factors such as food availability are the main factors controlling habitat quality. [source] No association between partial depopulation and Campylobacter spp. colonization of Dutch broiler flocksLETTERS IN APPLIED MICROBIOLOGY, Issue 3 2005A.D. Russa Abstract Aims:, To determine whether an association exists between partial depopulation of a flock and increased Campylobacter colonization in that flock. Methods and Results:, Data from 1737 flocks of two Dutch integrators were used. Flocks that experienced partial depopulation were defined as ,exposed' and those that did not as ,nonexposed'. Multivariable modelling was accomplished with, in addition to ,exposure', the independent variables ,age of broilers at slaughter' and ,season' to adjust for possible confounding. The response variable was ,Campylobacter colonization'. The odds ratio (OR) for partial depopulation for integrator A was 0·8 [95% CI (0·4, 1·8)]; for integrator B the OR = 0·8 [95% CI (0·5, 1·3)]. Age and season were confounders: the difference in Campylobacter status between exposed and nonexposed flocks of integrator A could be explained by both variables; for integrator B, only season was associated with Campylobacter status. Conclusions:, We found no significant association between partial depopulation and an increased risk of Campylobacter colonization among broiler flocks at final depopulation. Significance and Impact of the Study:, This study demonstrates that Campylobacter colonization in a broiler flock is not influenced by the partial depopulation of that flock. [source] Financial modelling of the potential cost of ovine Johne's disease and the benefit of vaccinating sheep flocks in southern New South WalesAUSTRALIAN VETERINARY JOURNAL, Issue 10 2008RD Bush Objective To develop an enterprise gross margin (GM) model that predicts the on-farm financial impact of ovine Johne's disease (OJD) for various sheep enterprises in Australia. In addition, to estimate the benefits and costs of control through the use of the GudairÔ vaccination, including a breakeven point. Design and population Data for the model was gained from an observational study conducted over a 3-year period from 2002 to 2004 using sheep from 12 OJD-infected flocks from southern New South Wales. Flocks ranged between 3500 and 20,000 sheep, with owner estimates of 5% or greater OJD mortality at the start of the study. Procedure A GM model was developed to predict the on-farm financial impact of OJD for various sheep enterprises in Australia, comparing non-infected, infected (status quo) and infected (vaccination) disease scenarios. Results Vaccination breakeven points are achieved within 2 to 3 years for breeding enterprises if OJD mortalities are high, rising towards 7 years for a Merino ewe enterprise if OJD mortalities are low. Conclusion The GM model demonstrates the returns to investment of vaccination for Australian sheep producers with OJD-infected flocks. [source] Regional and local influence of grazing activity on the diversity of a semi-arid dung beetle communityDIVERSITY AND DISTRIBUTIONS, Issue 1 2006Jorge M. Lobo ABSTRACT This study analyses the effect of resource availability (i.e. sheep dung) on dung beetle communities in an arid region of Central Spain, both at regional and at local scales. A total of 18 sites within 600 km2 were sampled for the regional analysis and 16 sites within the 30 km2 of an Iberian municipality were sampled for the local analysis. Spatial and environmental characteristics of sampling sites were also compiled at both scales, including measures of grazing activity (livestock density at regional scale, and two counts of rabbit and sheep dung at local scale). At a regional scale, any environmental or spatial variable can help to explain the variation in abundance. However, species richness was related to summer precipitation and composition was related to elevation. At local scale, abundance is not significantly related to any of the environmental variables, but species richness was related to the local amount of sheep dung (27% of variance). The amount of dung in a 2-km buffer around the site accounts for 27,32% of variance in abundance and 60,65% of variance in species richness. The presence of the flock with the highest sheep density explains 53% of abundance variability and 73% of species richness variance. A cluster analysis of localities identified two main groups, one characterized by a lower abundance and species richness that can be considered a nested subsample of the species-rich group. The mean and maximum amount of sheep dung in the sites separated by less than 2 km are the only significant explanatory variables able to discriminate both groups. These results suggest that grazing intensity (and the associated increase in the amount of trophic resources) is a key factor in determining local variation in the diversity and composition of dung beetle assemblages. However, dung beetle assemblages are not spatially independent at the analysed resolution, and the amount of dung in the surroundings seems to be more important for locally collected species than the dung effectively found in the site. Although differences in the availability and quantity of trophic resources among nearby sites could be affecting the population dynamics and dispersion of dung beetles within a locality, sites with larger populations, and greater species numbers would not be able to exercise enough influence as to bring about a complete local faunistic homogenization. [source] The ,vigorous rule' of Bishop Lull: between Bonifatian mission and Carolingian church controlEARLY MEDIEVAL EUROPE, Issue 3 2005James Palmer This paper argues that the reputation of St Boniface, one of the ,founders of Christian Europe', needs to be understood in relation to the career of Lull of Mainz, the saint's pupil and successor. It analyses Lull's literary, pastoral and missionary interests, as well as his political networks, to illustrate how he helped give form to the legends of Boniface and, in particular, Willibald's Vita Bonifatii and the Bonifatian letter collections. Study of the commemoration of Lull, principally in Mainz, Fulda, Hersfeld and Malmesbury, also reveals much about the ways Lull used the cult of Boniface to pursue a ,vigorous rule' over his flock in Mainz and in the process alienate many contemporaries. [source] The Effect of Within-Flock Spatial Position on the Use of Social Foraging Tactics in Free-Living Tree SparrowsETHOLOGY, Issue 3 2008Ferenc Mónus The benefit of producer (searches for own food) or scrounger (exploits the others' food discoveries) foraging tactic in a group of socially feeding animals may depend on where the individual searches for food within the group. Scrounging may be more advantageous in the centre of the group, having more individuals around to join, while producing may be more beneficial at the edges, where more unexplored food patches may be found. This study shows within-flock position correlates with foraging tactic use of feeding birds in socially foraging tree sparrows, Passer montanus. Sparrows staying closer to the centre of the flock found their food patches more frequently by joining (i.e. use more frequently the scrounging tactic) than those staying toward the edges. To our knowledge this is the first field study demonstrating the relationship between spatial position and foraging tactic use. We investigated this relationship under different perceived predation hazard, and found that under elevated risk of predation, central individuals may increase their use of joining more than individuals on the periphery of the flock. Moreover, we show that extremely specialized use of searching tactics may be very infrequent in tree sparrows. As both within-flock position and search tactic use can be altered very quickly and without leaving the flock, individuals may easily alter them in order to adjust their behaviour. [source] Age-Related Microhabitat Segregation in Willow Tit Parus montanus Winter FlocksETHOLOGY, Issue 11 2000Lluís Brotons It is expected that through flexibility in behaviour, flock living birds respond to the asymmetries in resource access derived from dominance relationships. We analysed the microhabitat use of willow tits in winter flocks and assessed possible factors which shape habitat segregation between adults and juveniles in different temperature regimes. When foraging in mild conditions (ambient temperature >,0°C), flocks split up into subgroups with adults foraging in inner parts of trees more often than juveniles. However, no differences were recorded in the vertical position occupied in trees. In harsh conditions (< , 4°C), flocks re-united and juveniles further moved to outer parts of trees, increasing horizontal segregation between age classes. In mild conditions, vigilance behaviour was not related to the position of birds in trees, but in harsh conditions, scanning frequency was higher in outer parts of trees only for adults. In mild weather, juvenile position in trees was associated with body size and mass. The foraging microhabitat segregation detected in harsh conditions fits the age-related hoarding distribution previously described in the same population. This supports the hypothesis that hoarded food is important in determining future foraging habitat use. Adult preference and intraspecific competition for safer or richer inner parts of trees as foraging sites during harsh conditions seems to determine the habitat segregation between adults and juveniles. Furthermore, we suggest that in mild weather, when foraging in the absence of adults, juveniles balance the costs of using a potentially dangerous microhabitat with the benefits of building energetically cheap and large food reserves through hoarding. The expected patterns of microhabitat segregation may differ in parids, depending on whether predation risk or other factors such as food availability are the main factors controlling habitat quality. [source] PHYLOGEOGRAPHY AND DEMOGRAPHY OF SYMPATRIC SISTER SURFPERCH SPECIES, EMBIOTOCA JACKSONI AND E. LATERALIS ALONG THE CALIFORNIA COAST: HISTORICAL VERSUS ECOLOGICAL FACTORSEVOLUTION, Issue 2 2005Glacomo Bernardi Abstract With 18 closely related endemic species that radiated in a diversity of ecological niches, the California surfperches (Embiotocidae) species flock is a good candidate for the study of sympatric speciation. Resource partitioninghas been suggested as an important driving force in the radiation of the surfperch family. Within the family, two congeneric sister species, Embiotoca jacksoni and E. lateralis, are known to compete strongly for a preferred singleood resource and may be used as a model of ecological interactions for the family. Along the California coast, the distribution of the two species differs. Embiotoca jacksoni has a continuous range, whereas E. lateralis shows a disjunction with a distribution gap in the Southern California Bight. Two hypotheses may explain this disjunct distribution. Ecological competition may have displaced E. lateralis in favor of E. jacksoni. Alternatively, a common vicariant event may have separated the species into northern and southern populations, followed by secondary contactin E. jacksoni but not in E. lateralis. The two hypotheses predict different phylogeographic and demographic signatures. Using a combined phylogeographic and coalescent approach based on mitochondrial control region data, we show that vicariance can only account for a portion of the observed divergences. Our results are compatible with a significant role played by ecological competition in the southern range of the species. [source] New ovine PrP gene haplotypes as a result of single nucleotide polymorphisms in the PrP gene promoterJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 2 2005G.T. O'Neill Summary Incidence of scrapie in sheep is strongly associated with PrP gene amino acid codon variants at positions 136, 154 and 171. However, there are breed differences in disease linkage and anomalous disease patterns which cannot obviously be explained by the ,3 codon' genotype. Mouse studies indicate that PrP protein levels can influence scrapie disease progression and this prompted us to study the sheep PrP gene promoter region in a search for novel polymorphisms which may influence gene expression and hence disease susceptibility. The incidence of three single nucleotide polymorphisms (SNP) at positions C/A-5354, T/C-5382 and C/G-5622 within the PrP gene promoter region was determined from Neuropathogenesis Unit (NPU) and New Zealand (NZ) Cheviot and UK and NZ Suffolk sheep. The SNP variants A-5354 and G-5622 created consensus sequences for STAT and SP1 transcription factors, respectively, and C-5382 was within Motif 1, one of four conserved motifs found within the promoter region of mammalian PrP genes. The occurrence of C/A-5354 and T/C-5384 SNP exhibited differential associations with the PrP open reading frame (ORF) variants linked to scrapie susceptibility. A significant imbalance in the incidence of the C-5354/AXQ haplotype was found in the NPU Cheviot flock. C-5382 was not found in Suffolk sheep of either UK or NZ origin. The G-5622 SNP was found at a lower incidence in Suffolk sheep compared with Cheviots. The range of transcription factor binding motif profiles in the PrP gene promoter may act to modulate PrP gene activity and warrants further large-scale study. [source] Contrasting interference functions and foraging dispersion in two species of shorebird (Charadrii)JOURNAL OF ANIMAL ECOLOGY, Issue 2 2000Michael G. Yates Summary 1.,Above a threshold density of , 100 birds ha -1, strong interference occurred between redshank Tringa totanus (Linnaeus) feeding by sight on the amphipod crustacean Corophium volutator (Pallas). No aggressive interactions occurred between the birds and the probable cause was prey depression. 2.,Redshank fed in a square metre of mud that had recently been exploited by another redshank much less often than would be expected by chance. By avoiding areas where prey would have been recently exploited, the feeding rate of redshank was up to three times faster than it would have been had they not avoided other foraging redshank. 3.,Bar-tailed godwit fed in a square metre of mud that had been recently exploited by another godwit much more often than would be expected by chance in randomly moving birds. They tended to flock while foraging and showed no tendency to avoid areas where prey would have been recently exploited. 4.,There was no evidence that interference occurred between bar-tailed godwit Limosa lapponica (Linnaeus) feeding on the polychaete lugworm Arenicola marina (Linnaeus) at densities below 300 birds ha -1, even though aggressive interactions occurred between birds. [source] Effect of induced body condition score differences on physiological response, productive and reproductive performance of Malpura ewes kept in a hot, semi-arid environmentJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 2 2010V. Sejian Summary This study was undertaken to study the influence of induced body condition score (BCS) differences on physiological response, productive and reproductive performance of Malpura ewes to optimise BCS for these ewes for maximising production making it economically viable. The study was conducted for a period of 1 year using thirty healthy Malpura ewes (2,4 year old). The animals were randomly divided and different BCS was induced within three groups named Group I (BCS 2.5; n = 10), Group II (BCS 3.0,3.5; n = 10) and Group III (BCS 4.0; n = 10). The parameters included in the study were allometric measurements, physiological response, wool yield and reproductive performance. BCS had a significant influence on allometric measurements, respiration rate and different reproductive parameters studied, while wool production differed significantly during spring and non-significantly during autumn. The results revealed that the reproductive performance of Malpura ewes with a BCS of 3.0,3.5 was better in comparison with the groups with lower and higher BCS. It may be concluded from this study that an active management of breeding sheep flock to achieve a BCS of 3.0,3.5 may prove to result in an economically viable return from these flocks. [source] Influence of crop residue ration supplementation on the attainment of puberty and postpartum reproductive activities of Red Sokoto goatsJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 1-2 2005B. S. Malau-Aduli Summary The general objective of this study was to come up with an appropriate, affordable and locally available crop residue supplementation package that would enhance reproductive performance in small ruminants. Specifically, 28 Red Sokoto weaner does between 3 and 4 months of age weighing between 2 and 3 kg were used in the first experiment to determine the influence of crop residue supplementation on age and weight at puberty as determined by blood progesterone levels. In the second experiment, another 28 adult does (,2 years old) of the same breed in the same flock with lactation numbers between 1 and 3 were used to determine the length of postpartum acyclic period. In both experiments, a 3 × 2 factorial experimental design comprising three dietary supplements (A, B, C) at two feeding levels (1% and 2% of body weight) fed in addition to a basal diet of Digitaria smutsii hay and natural pasture ad libitum with an unsupplemented negative control group (D) and four goats per treatment was utilized. In ration A, a conventional concentrate supplement consisting of maize, wheat offal, cottonseed cake and bonemeal was utilized; in rations B and C, the supplement consisted of guinea-corn bran, cowpea husk and groundnut haulms; and maize offal, groundnut shells and groundnut haulms respectively. Unsupplemented (ration D) weaner does reached puberty at a later age and had lighter body weights than all the others. Weaner does on ration 2A (concentrate fed at 2% of body weight) attained puberty at the earliest age and heaviest body weight, although the age at puberty was not significantly different from those on rations 1A (concentrate fed at 1% body weight), 1C and 2C. Blood progesterone profiles before and after puberty ranged from 0.05 to 9.0 ng/ml, respectively, and was highest in does fed rations A and C and least in the unsupplemented does. The mean interval between kidding and initiation of ovarian activity was 54.28 ± 17.61 days and the mean interval between kidding and conception was 63.04 ± 25.34 days. Only 25% of the unsupplemented does conceived again during the period under study compared with 100% in rations 1A, 2A, 1C and 2C; 75% in ration 2B and 50% in ration 1B. It was concluded that implementation of supplementary feeding in the dry season improves reproductive performance in the Red Sokoto doe. Furthermore, ration C, a crop residue-based ration, was a suitable dry season supplementation alternative to the expensive conventional concentrate ration for the smallholder goat farmer in the subhumid tropics of Nigeria. [source] Detection and survival of Campylobacter in chicken eggsJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2003O. Sahin Abstract Aims:Campylobacter jejuni, a food-borne human pathogen, is widespread in poultry; however, the sources of infection and modes of transmission of this organism on chicken farms are not well understood. The objective of this study was to determine if vertical transmission of C. jejuni occurs via eggs. Methods and Results: Using a temperature differential method, it was shown that Campylobacter had limited ability to penetrate the eggshell. When C. jejuni was directly inoculated into the egg yolk and the eggs were stored at 18°C, the organism was able to survive for up to 14 days. However, viability of C. jejuni was dramatically shortened when injected into the albumen or the air sac. When freshly laid eggs from Campylobacter -inoculated specific pathogen-free (SPF) layers were tested, C. jejuni -contamination was detected in three of 65 pooled whole eggs (5,10 eggs in each pool) via culture and PCR. However, the organism was not detected from any of the 800 eggs (80 pools), collected from the same SPF flock, but kept at 18°C for 7 days before testing. Likewise, Campylobacter was not recovered from any of 500 fresh eggs obtained from commercial broiler-breeder flocks that were actively shedding Campylobacter in faeces. Also, none of the 1000 eggs from broiler breeders obtained from a commercial hatchery were positive for Campylobacter. Conclusions: These results suggest that vertical transmission of C. jejuni through the egg is probably a rare event and does not play a major role in the introduction of Campylobacter to chicken flocks. Significance and Impact of the Study: Control of Campylobacter transmission to chicken flocks should focus on sources of infection that are not related to eggs. [source] Comparative rates of lower jaw diversification in cichlid adaptive radiationsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 7 2010C. D. HULSEY Abstract The lower jaw (LJ) provides an ideal trophic phenotype to compare rates and patterns of macroevolution among cichlid radiations. Using a novel phylogeny of four genes (ND2, dlx2, mitfb, and s7), we examined the evolutionary relationships among two of the most phylogenetically disparate cichlid radiations: (i) the Central America Heroines; and (ii) the East African Lake Malawi flock. To quantify jaw morphology, we measured two LJ lever systems in approximately 40 species from each lineage. Using geologic calibrations, we generated a chronogram for both groups and examined the rates of jaw evolution in the two radiations. The most rapidly evolving components of the LJ differed between the two radiations. However, the Lake Malawi flock exhibited a much faster rate of evolution in several components of the LJ. This rapid rate of divergence is consistent with natural selection, promoting unparalleled trophic diversification in Lake Malawi cichlids. [source] Shepherds of science: Shear the flock not skin themJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 8 2002Rakesh K Tandon No abstract is available for this article. [source] No association between partial depopulation and Campylobacter spp. colonization of Dutch broiler flocksLETTERS IN APPLIED MICROBIOLOGY, Issue 3 2005A.D. Russa Abstract Aims:, To determine whether an association exists between partial depopulation of a flock and increased Campylobacter colonization in that flock. Methods and Results:, Data from 1737 flocks of two Dutch integrators were used. Flocks that experienced partial depopulation were defined as ,exposed' and those that did not as ,nonexposed'. Multivariable modelling was accomplished with, in addition to ,exposure', the independent variables ,age of broilers at slaughter' and ,season' to adjust for possible confounding. The response variable was ,Campylobacter colonization'. The odds ratio (OR) for partial depopulation for integrator A was 0·8 [95% CI (0·4, 1·8)]; for integrator B the OR = 0·8 [95% CI (0·5, 1·3)]. Age and season were confounders: the difference in Campylobacter status between exposed and nonexposed flocks of integrator A could be explained by both variables; for integrator B, only season was associated with Campylobacter status. Conclusions:, We found no significant association between partial depopulation and an increased risk of Campylobacter colonization among broiler flocks at final depopulation. Significance and Impact of the Study:, This study demonstrates that Campylobacter colonization in a broiler flock is not influenced by the partial depopulation of that flock. [source] Isolation of Shiga toxin-producing Escherichia coli O103 from sheep using automated immunomagnetic separation (AIMS) and AIMS-ELISA: sheep as the source of a clinical E. coli O103 case?LETTERS IN APPLIED MICROBIOLOGY, Issue 3 2002A.M. Urdahl Aims: To investigate whether a sheep flock was the original reservoir of a Shiga toxin-producing Escherichia coli (STEC) O103 strain causing a clinical human case and to compare the two diagnostic methods automated immunomagnetic separation (AIMS) and AIMS-ELISA. Methods and Results: AIMS detected Escherichia coli O103 in 36·5% of the samples and AIMS-ELISA detected E. coli O103 in 52·1% of the samples. Polymerase chain reaction detected stx1 and eae in three of 109 E. coli O103 isolates. Pulsed field gel electrophoresis showed that the sheep and human STEC O103 were characterized by distinctly different profiles. Conclusions: The sheep flock was shown to carry STEC O103, although an association between the sheep flock and the clinical human case could neither be proven nor eliminated. Substantial agreement was found between AIMS and AIMS-ELISA, but AIMS-ELISA was less time consuming and resulted in a higher recovery of E. coli O103. Significance and Impact of the Study: The study shows that sheep may be carriers of STEC that are associated with human disease and that the methods described can be used to increase the sensitivity of STEC detection. [source] Genetic and ecological divergence of a monophyletic cichlid species pair under fully sympatric conditions in Lake Ejagham, CameroonMOLECULAR ECOLOGY, Issue 6 2001Ulrich Schliewen Abstract Although there is mounting evidence that speciation can occur under sympatric conditions, unambiguous examples from nature are rare and it is almost always possible to propose alternative allopatric or parapatric scenarios. To identify an unequivocal case of sympatric speciation it is, therefore, necessary to analyse natural settings where recent monophyletic species flocks have evolved within a small and confined spatial range. We have studied such a case with a cichlid species flock that comprises five Tilapia forms endemic to a tiny lake (Lake Ejagham with a surface area of approximately 0.49 km2) in Western Cameroon. Analysis of mitochondrial D-Loop sequences shows that the flock is very young (approximately 104 years) and has originated from an adjacent riverine founder population. We have focused our study on a particular pair of forms within the lake that currently appears to be in the process of speciation. This pair is characterized by an unique breeding colouration and specific morphological aspects, which can serve as synapomorphic characters to prove monophyly. It has differentiated into a large inshore and a small pelagic form, apparently as a response to differential utilization of food resources. Still, breeding and brood care occurs in overlapping areas, both in time and space. Analysis of nuclear gene flow on the basis of microsatellite polymorphisms shows a highly restricted gene flow between the forms, suggesting reproductive isolation between them. This reproductive isolation is apparently achieved by size assortative mating, although occasional mixed pairs can be observed. Our findings are congruent with recent theoretical models for sympatric speciation, which show that differential ecological adaptations in combination with assortative mating could easily lead to speciation in sympatry. [source] Prospecting for (Campaign) GoldAMERICAN JOURNAL OF POLITICAL SCIENCE, Issue 2 2007Wendy K. Tam Cho Campaigns and political parties are faced with the immensely important practical challenge of financing their efforts. Raising money is instrumental to all other aims. In recent years, this task has been complicated by the need to enlist ever greater numbers of contributors to raise ever larger sums of money. At the same time, fundraising burdens are eased a bit because contributors flock together. That is, campaign contributing is a spatially dependent phenomenon, associated with affluence and the presence of networks. Accordingly, geospatial tools provide a helpful method for understanding and predicting where contributions can be most successfully mined. [source] Conservation breeding for reintroductions: assessing survival in a captive flock of houbara bustardsANIMAL CONSERVATION, Issue 3 2001Yolanda van Heezik Conservation breeding for reintroduction is becoming a popular option for restoring threatened populations. Whereas post-release results are widely reported in the conservation literature, little empirical information is presented on the captive populations that often make such releases possible, even though fecundity, fertility and survival rates can have an impact on the outcome and cost of wild population re-establishment. We present results of survival analyses carried out on a captive population of houbara bustards to determine peak periods of mortality, and by identifying sources of variations in mortality to recognize the potential impact of management practices on productivity. There were two main mortality peaks: during incubation (53% survival of fertile eggs), and by 6 months post-hatching (75% survival of hatchlings). Management-related variables influencing survival of eggs and chicks included the year when laid, the cohort of females laying them, and possibly sex. Most post-hatching deaths were due to trauma and infectious diseases. Trauma-related deaths usually follow collisions with cages, and imply selection for the captive environment, an undesirable trend in populations maintained for reintroductions. Reducing losses during incubation would have the largest impact on production of birds for reintroduction, enabling the release of more birds, and reducing the overall costs of the project. [source] Genetic mapping of quantitative trait loci for milk production in sheepANIMAL GENETICS, Issue 5 2010R. G. Mateescu Summary A backcross pedigree using dairy East Friesian rams and non-dairy Dorset ewes was established specifically to map quantitative trait loci (QTL) affecting milk production in sheep. Ninety nine microsatellite markers of an initial set of 120 were successfully genotyped and informative on 188 animals of this backcross pedigree. Test-day milk records on individual ewes were used to estimate several milk yield related traits, including peak milk yield and cumulative milk yield to 50 (MY50), 100 (MY100) and 250 days (MY250). These traits, as well as estimated breeding value of backcross ewes extracted from the genetic evaluation file of the entire flock, were used in interval mapping. Ovine chromosomes 2, 12, 18, 20 and 24 were identified to harbour putative QTL for different measures of milk production. The QTL on Ovis aries chromosomes (OAR) 2 and 20 mapped to locations where similar trait QTL have already been mapped in other studies, whereas QTL on OAR 12, 18 and 24 were unique to our backcross pedigree and have not been reported previously. In addition, all identified QTL regions were syntenic with bovine chromosomal segments revealed to harbour QTL affecting milk production traits, providing supporting evidence for the QTL identified here. [source] Genetic mapping of quantitative trait loci for resistance to Haemonchus contortus in sheepANIMAL GENETICS, Issue 3 2009K. Marshall Summary This paper presents results from a mapping experiment to detect quantitative trait loci (QTL) for resistance to Haemonchus contortus infestation in merino sheep. The primary trait analysed was faecal worm egg count in response to artificial challenge at 6 months of age. In the first stage of the experiment, whole genome linkage analysis was used for broad-scale mapping. The animal resource used was a designed flock comprising 571 individuals from four half-sib families. The average marker spacing was about 20 cM. For the primary trait, 11 QTL (as chromosomal/family combinations) were significant at the 5% chromosome-wide level, with allelic substitution effects of between 0.19 and 0.38 phenotypic standard deviation units. In general, these QTL did not have a significant effect on faecal worm egg count recorded at 13 months of age. In the second stage of the experiment, three promising regions (located on chromosomes 1, 3 and 4) were fine-mapped. This involved typing more closely spaced markers on individuals from the designed flock as well as an additional 495 individuals selected from a related population with a deeper pedigree. Analysis was performed using a linkage disequilibrium,linkage approach, under additive, dominant and multiple QTL models. Of these, the multiple QTL model resulted in the most refined QTL positions, with resolutions of <10 cM achieved for two regions. Because of the moderate size of effect of the QTL, and the apparent age and/or immune status specificity of the QTL, it is suggested that a panel of QTL will be required for significant genetic gains to be achieved within industry via marker-assisted selection. [source] Black sheep among the flock of protein structuresACTA CRYSTALLOGRAPHICA SECTION D, Issue 1 2010Zbigniew Dauter First page of article [source] Do birds of a feather universally flock together?ASIAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 4 2009Cultural variation in the similarity-attraction effect Three experiments explored the similarity-attraction effect (SAE) among North American and Japanese samples. In all studies, North Americans showed a significantly more pronounced SAE than the Japanese. The North Americans consistently revealed a strong SAE whereas the Japanese effect was only significant in the methods with the most power. The cultural differences emerged across different methods, and for the domains of personality, activities, attitudes and demographics. The cultural difference was mediated by self-esteem, indicating that a motivation for positive self-views is a mechanism underlying the SAE. [source] Economic management of anthelmintic resistance: model and application,AUSTRALIAN JOURNAL OF AGRICULTURAL & RESOURCE ECONOMICS, Issue 4 2009Caris L. Pech The increasing prevalence of anthelmintic (drench) resistance in gastrointestinal parasite populations is decreasing the profitability of the Australian sheep industry. Refugia management can delay its development by not exposing a proportion of the worm population to chemical control. A dynamic-optimisation model is used to assess the economic value of refugia for management of the worm species Teladorsagia circumcincta and macrocyclic lactone drenches in an application to Western Australian sheep flocks. A low rate of refugia (2 per cent) is most profitable under standard circumstances because it slows the development of resistance, but also reduces the proportion of the flock not exposed to chemical control. Frequent drench application should remain the primary method of control. However, its efficacy should be preserved through refugia management, rather than greatly reducing treatment frequency. [source] Seroconversion to avian influenza virus in free-range chickens in the Riverland region of VictoriaAUSTRALIAN VETERINARY JOURNAL, Issue 8 2010IJ East Background Since 2005, H5N1 avian influenza (AI) has spread from South-East Asia to over 60 different countries, resulting in the direct death or slaughter of over 250,000,000 poultry. Migratory waterfowl have been implicated in this spread and in Australia there have been numerous isolations of low-pathogenicity AI virus from wild waterfowl and shorebirds. The Department of Human Services, Victoria maintains 10 sentinel free-range chicken flocks in the Riverland at locations that are populated by large numbers of waterfowl known to carry a range of strains of AI. Objective This study analysed historical samples collected in 1991,94 and 2003,06 from the library of serum samples for antibodies against AI to assess the potential for transfer of AI virus from wild waterfowl to free-range poultry. Results Of the 2000 serum samples analysed, 17 were positive for antibodies against AI and 87 were suspect, with a clustering of positive and suspect results in the years 1994, 2003 and 2004. There was also a clustering of positive samples at the site of the Barmah flock. Nine sequential sets of sera from individual chickens with at least one positive result were identified. Analysis of these sequential sets showed that infection was acquired on site but that the antibody response to AI infection was short-lived and was no longer detectable at 8 weeks after the positive finding. Conclusion The surveillance of sentinel chickens is a potential avenue for monitoring the circulation of AI viruses and could provide an early warning system for the commercial poultry industries. [source] Risk factors for post-weaning mortality of Merino sheep in south-eastern AustraliaAUSTRALIAN VETERINARY JOURNAL, Issue 8 2009AJD Campbell Objective To measure associations between body weight, growth rate, sex, time of shearing and post-weaning mortality of Merino sheep. Design Uni- and multivariable survival analyses of sheep mortality during the first year after weaning, using records (n = 3657) from two field experiments conducted in Western Victoria from 1996 to 2003. Results Overall mortality was 14.3% (range 4.5,26.8%) and mean maximum mortality rate was 29 deaths/1000 weaners/month. Increased mortality risk was associated with decreases in fleece-free body weight and mean weaner growth rate, particularly at low weights and growth rates. Weaners in the lightest weaning weight quintile had a hazard ratio of 3.5, compared with the middle quintile. The hazard ratio for a 2-kg decrease in weaning weight was 1.2 to 1.7 for weaners lighter than 22 kg. The hazard ratio for a reduction in mean weaner growth rate in the first 5 months after weaning of 0.25 kg/month was 1.1 to 6.8 if mean growth rate was less than 1 kg/month, but did not differ significantly from 1 at greater growth rates. The hazard ratio for wether weaners was approximately 1.5 compared with ewe weaners. The hazard ratio for weaners shorn between December and May, compared with unshorn weaners, was 1.2 to 3.5, with the greatest risk difference associated with shearing in March (45 deaths/1000 weaners/month). Conclusion Improving the body weight and mean growth rate of weaner sheep is likely to reduce post-weaning mortality. Lightweight weaners in a flock should be managed separately from the main portion after weaning. In southern Australia, not shearing spring-born Merino weaners between December and May may assist in reducing overall post-weaning mortality. [source] A serological and virological survey for evidence of infection with Newcastle disease virus in Australian chicken farmsAUSTRALIAN VETERINARY JOURNAL, Issue 6 2007VG Kite Objective, To determine the prevalence and distribution of antibodies to Newcastle disease virus on Australian chicken farms and to determine the pathotype and relationships of the Newcastle disease viruses present on those farms. Design, A cross-sectional survey of 753 commercial chicken farms. Procedure, The survey comprised a detailed questionnaire and collection of venous blood samples. The titre of antibodies to Newcastle disease virus was determined by haemagglutination inhibition. Virus isolation was conducted from cloacal and tracheal swabs taken from chickens in serologically positive flocks. Virus isolates were pathotyped on the basis of the deduced Fusion protein cleavage site determined by nucleotide sequencing of a 265 bp region of the genome in the region of the cleavage site. Results, Antibody evidence of Newcastle disease virus infection was found on 300 of the 753 surveyed farms throughout all 11 geographic regions of the survey. The highest prevalence occurred in the Sydney basin, New South Wales and Victoria east regions. Antibody titres were also highest in the regions where serologically positive flocks were most prevalent. The 259 virus isolates revealed nine different RNA sequences. Of the nine virus groups isolated, the most common group W was identical in sequence to the V4 vaccine strain. Five of the other groups had novel RNA sequences in the region of the F protein cleavage site. Conclusions, Antibodies to Newcastle disease virus are highly prevalent in the Australian chicken flock but all identified strains were avirulent in nature. [source] | ||||||||||||||||||||||||||||||||||