Incidence of reinfections with Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae in pig farms located in respiratory-disease-free regions of Switzerland--identification and quantification of risk factors

The objective of the study was to identify risk factors for reintroduction of Actinobacillus pleuopneumoniae and Mycoplasma hyopneumoniae (enzootic pneumonia) onto pig farms in areas in Switzerland that were involved in an eradication programme from 1996 to 1999 and to assess the role of dealers in relation to these reinfections. The study was based on the comparison of pig farms that were reinfected in the year 2000 (cases) and pig farms that remained uninfected in the same area (controls). Additionally, data were collected from Swiss pig dealers and transport companies. Out of a total of 3983 farms, 107 farms were reinfected in the year 2000. The incidences were 0.1% for Actinobacillus pleuopneumoniae and 2.6% for Mycoplasma hyopneumoniae (enzootic pneumonia). Compared to reinfection rates prior to the eradication programme, this is a considerable reduction. Statistically significant risk factors for the reinfection were 'finishing farm', 'large mixed breeding-finishing farm', 'reinfected neighbour' and 'parking site for pig transport vehicles close to the farm'. Pig farmers that purchased pigs from only one supplier per batch had a lower risk of reintroducing infection (protective factor). As long as infected and uninfected regions co-exist in Switzerland, direct and indirect contact between farms, pig herds and slaughter sites via transport vehicles are a major pathway of disease spread. Risk management measures linked to these contacts are therefore of key importance. The survey of dealers indicated various areas for improvement such as strategic planning of pick-up routes or cleaning and disinfecting of trucks.     

Persistent activity of doramectin and ivermectin in the prevention of cutaneous myiasis in cattle experimentally infested with Cochliomyia hominivorax

A study was conducted to evaluate the activity of a single administration of doramectin or ivermectin against severe, induced infestations of Cochliomyia hominivorax. Twenty-four Holstein bull calves were allocated to four groups of six animals each and treated either with saline, doramectin 1%, or either one of two formulations of ivermectin 1% at a dose rate of 200 microg/kg. On Day 12 after treatment, each calf was anesthetized and two wounds were created on the left side of the shoulder and rump of each calf and 2 h later, each wound was implanted with 100 newly hatched larvae of C. hominivorax. On Day 15 after treatment, the procedure was repeated on the right side of each calf. Wounds were examined daily for 5 days and evidence of live larvae was recorded. Doramectin provided reduction in myiasis of 90.9 and 83.3% at 12 and 15 days after treatment, respectively, compared to the saline control treatment (P < 0.0001). In contrast, there were no significant differences in the number of calves with myiasis between those treated with either of the ivermectin formulations and the saline control.     

Polyuria and Polydipsia and Disturbed Vasopressin Release in 2 Dogs With Secondary Polycythemia

In dogs, secondary polycythemia (SP) may be associated with polyuria and polydipsia (PU/PD). The pathogenesis of this PU/PD has not yet been explained. We hypothesized that hyperviscosity and increased blood volume in SP might affect vasopressin (VP) release, resulting in PU/PD. This hypothesis was tested in 2 dogs with SP caused by renal neo-plasia and PU/PD. Osmoregulation of VP release was studied by a modified water deprivation test and by investigating the VP response to hypertonic saline infusion.
Water deprivation test results were consistent with an inability to produce concentrated urine despite increasing plasma osmolality. During hypertonic saline infusion, the osmotic threshold of VP release was markedly increased in both dogs, resulting in a delayed VP response to increasing plasma osmolality. The sensitivity of VP release was low normal in both dogs. We conclude that blood hyperviscosity and increased blood volume led to impaired VP release and polyuria.     

Resistenzeigenschaften im Gersten- und Weizensortiment Gatersleben 20. Prüfung des Verhaltens von Gersten gegen Flugbrand,Ustilago nuda (Jens.) Rostr.

Zusammenfassung In den Jahren 1964 bis 1974 wurden 362 Winter- und 738 Sommergersten mit einer lokalen Population vonUstilago nuda geprüft. Zur Kennzeichnung der Virulenz des Infektionsmaterials ist das Verhalten von Trägern bekannter Resistenzgene angegeben. Resistenz (0 ... 10% Befall) zeigten 197 oder 18% der 1100 Gersten. Mäßig resistent bis mäßig anfällig (>10 ... 30% Befall) waren 146 oder 13% dieses Sortiments. Als anfällig wurden 69% der Kollektion bewertet.Im Zusammenhang mit diesen Ergebnissen wird auf die Literatur zur Genetik der Flugbrandresistenz und auf Kombinationen mit anderen Resistenzmerkmalen eingegangen.

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Resistance in the Gatersleben barley and wheat collection. 20. Testing of barley for reaction to loose smut,Ustilago nuda (Jens.) Rostr.

Summary During the years 1964–74 362 winter and 738 spring barleys were inoculated with a local smut population. Its virulence is described by the reactions of varieties with identified resistance genes.Of the 1100 varieties tested 197 were resistant (0 ... 10% infection), 146 showed >10 ... 30% infection, and 69 per cent of this collection were classified as susceptible, with infection exceeding 30%.In connection with these results literature on smut resistance and the combination with resistance to other diseases are discussed.

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. 20. , Ustilago nuda (Jens.) Rostr.

1964 1974 . 362 738 Ustilago nuda. . ( 0 10%) 197 1100 (18%). ( 10 30%) 146 (13%). 69% . .

     

Recovery of saturated hydraulic conductivity under secondary succession on former pasture in the humid tropics

Landscapes in the humid tropics are undergoing a continuous change in land use. Deforestation is still taking its toll on forested areas, but at the same time more and more secondary forests emerge where formerly agricultural lands and pastures are being abandoned. Regarding soil hydrology, the extent to which secondary succession can recover soil hydrological properties disturbed by antecedent deforestation and pasture use is yet poorly understood. We investigated the effect of secondary succession on saturated hydraulic conductivity (Ks) at two soil depths (0-6 and 6-12 cm) using a space-for-time approach in a landscape mosaic in central Panama. The following four land-use classes were studied: pasture (P), secondary forest of 5-8 years of age (SF5), secondary forest of 12-15 years of age (SF12) and secondary forest of more than 100 years of age (SF100), each replicated altogether four times in different micro-catchments across the study region. The hydrological implications of differences in Ks in response to land-use change with land use, especially regarding overland flow generation, were assessed via comparisons with rainfall intensities.Recovery of Ks could be detected in the 0-6 cm depth after 12 years of secondary succession: P and SF5 held similar Ks values, but differed significantly (α = 0.05) from SF12 and SF100 which in turn were indistinguishable. Variability within the land cover classes was large but, due to sufficient replication in the study, Ks recovery could be detected nonetheless. Ks in the 6-12 cm depth did not show any differences between the land cover classes; only Ks of the uppermost soil layer was affected by land-use changes. Overland flow - as inferred from comparisons of Ks with rainfall intensities - is more likely on P and SF5 sites compared to SF12 and SF100 for the upper sample depth; however, generally low values at the 6-12 cm depth are likely to impede vertical percolation during high rainfall intensities regardless of land use.We conclude that Ks can recover from pasture use under secondary succession up to pre-pasture levels, but the process may take more than 8 years. In order to gain comprehensive understanding of Ks change with land use and its hydrological implications, more studies with detailed land-use histories and combined measurements of Ks, overland flow, precipitation and throughfall are essential.     

Factors influencing the intensification of farming systems and soil‐nutrient management in the rural‐urban continuum of SW Ghana

Farmers in Ghana use a variety of soil‐fertility management practices to optimize the benefits of shifting cultivation and/or to intensify their production. The research question was to analyze the relationship between these practices and the availability of the production factors land, labor, and capital. A farm survey along a gradient through SW Ghana showed that there is only a weak link between the intensification of traditional farming systems, population pressure, and reduced fallow periods as long as shifting cultivation is possible and common. Even where fallow periods reach a cut‐off point, farmers might look for land in remoter areas or invest in off‐farm activities. Only where market proximity supports the production of high‐value crops, investment flows are used to maintain continuous cultivation on favorable production sites, especially those with water access. The results verify the validity of the framework of agricultural‐systems dynamics in W Africa, developed by the International Institute of Tropical Agriculture (IITA) and the importance to distinguish between population‐driven and market‐driven situations. Both meet in periurban areas, which make them hot spots for research and development, while support for intensification is likely to fail where markets are far and shifting cultivation still an option.