Experimental study to determine if low-pathogenicity and high-pathogenicity avian influenza viruses can be present in chicken breast and thigh meat following intranasal virus inoculation

Two low-pathogenicity (LP) and two high-pathogenicity (HP) avian influenza (AI) viruses were inoculated into chickens by the intranasal route to determine the presence of the AI virus in breast and thigh meat as well as any potential role that meat could fill as a transmission vehicle. The LPAI viruses caused localized virus infections in respiratory and gastrointestinal (GI) tracts. Virus was not detected in blood, bone marrow, or breast and thigh meat, and feeding breast and thigh meat from virus-infected birds did not transmit the virus. In contrast to the two LPAI viruses, A/chicken/Pennsylvania/1370/1983 (H5N2) HPAI virus caused respiratory and GI tract infections with systemic spread, and virus was detected in blood, bone marrow, and breast and thigh meat. Feeding breast or thigh meat from HPAI (H5N2) virus-infected chickens to other chickens did not transmit the infection. However, A/lchicken/Korea/ES/2003 (H5N1) HPAI virus produced high titers of virus in the breast meat, and feeding breast meat from these infected chickens to other chickens resulted in Al virus infection and death. Usage of either recombinant fowlpox vaccine with H5 AI gene insert or inactivated Al whole-virus vaccines prevented HPAI virus in breast meat. These data indicate that the potential for LPAI virus appearing in meat of infected chickens is negligible, while the potential for having HPAI virus in meat from infected chickens is high, but proper usage of vaccines can prevent HPAI virus from being present in meat.     

An investigation into the practices of dairy producers and veterinarians in dehorning dairy calves in Ontario

The objective of this survey was to describe the current state of dehorning practices by dairy producers and veterinarians in Ontario and to identify opportunities to improve on existing practices. Two hundred and seven producers and 65 veterinarians completed a survey on dehorning practices during the summer of 2004. Seventy-eight percent of dairy producers dehorn their own calves; 22% use local anesthetics. Veterinarians dehorn calves for 31% of dairy clients; 92% use local anesthetics. Pain management was the most common reason for use of local anesthetics for both groups, while time (veterinarians) and time and cost (producers) were the most common reasons for lack of use. Producers who used local anesthetics were 6.5 times more likely to have veterinary involvement in their dehorning decisions. Thirteen percent of producers were unaware of the options for pain management. These results suggest that veterinarians should take the initiative to educate their clients about the options for pain management.     

Soil-plant hydrology of indigenous and exotic trees in an Ethiopian montane forest

Fast-growing exotic trees are widely planted in the tropics to counteract deforestation; however, their patterns of water use could be detrimental to overall ecosystem productivity through their impact on ecosystem water budget. In a comparative field study on seasonal soil-plant water dynamics of two exotic species (Cupressus lusitanica Mill. and Eucalyptus globulus Labill.) and the indigenous Podocarpus falcatus (Thunb.) Mirb. in south Ethiopia, we combined a 2.5-year record for climate and soil water availability, natural-abundance oxygen isotope ratios (delta(18)O) of soil and xylem water, destructive root sampling and transpiration measurements. Soil was generally driest under C. lusitanica with its dense canopy and shallow root system, particularly following a relatively low-rainfall wet season, with the wettest soil under E. globulus. Wet season transpiration of C. lusitanica was twice that of the other species. In the dry season, P. falcatus and C. lusitanica reduced transpiration by a factor of six and two, respectively, whereas E. globulus showed a fivefold increase. In all species, there was a shift in water uptake to deeper soil layers as the dry season progressed, accompanied by relocation of live fine root biomass (LFR) of C. lusitanica and P. falcatus to deeper layers. Under P. falcatus, variability in soil matric potential, narrow delta(18)O depth gradients and high LFR indicated fast water redistribution. Subsoil water uptake was important only for E. globulus, which had low topsoil LFR and tap roots exploiting deep water. Although P. falcatus appeared better adapted to varying soil water availability than the exotic species, both conifers decreased growth substantially during dry weather. Growth of E. globulus was largely independent of topsoil water content, giving it the potential to cause substantial dry-season groundwater depletion.     

Influence of native catfish mucus on Flavobacterium columnare growth and proteolytic activity

Flavobacterium columnare causes columnaris disease of farmed and wild freshwater fish. Skin mucus is an important factor in early stages of columnaris pathogenesis, albeit little studied. Our objectives were to (a) characterize the terminal glycosylation pattern (TGP) of catfish mucus, (b) determine the growth of F. columnare in formulated water (FW)‐containing channel catfish (Ictalurus punctatus) or hybrid catfish (Ictalurus punctatus X Ictalurus furcatus) mucus and (c) examine extracellular protease activity of two F. columnare isolates differing in virulence. The TGP of catfish mucus by lectin binding was as follows: alpha‐D‐mannose/alpha‐D‐glucose >N‐acetyl‐beta‐D‐glucosamine >N‐acetyl‐beta‐D‐glucosamine/N‐acetylneuraminic acid >N‐acetyl‐D‐galactosamine >alpha‐D‐galactose/N‐acetyl‐alpha‐D‐galactosamine >beta‐D‐galactose = alpha‐L‐fucose. Virulence studies demonstrated isolate AL‐02‐36 was highly virulent in channel catfish fry (0.1 g) with cumulative mortality of 90%‐100% versus 60% for isolate ALG‐00‐530 at equivalent doses (~3 × 10⁶ CFU/ml); a similar result was observed in larger (0.7 g) catfish. In multiple experiments, F. columnare replicated (2‐3 logs) and survived (28 days) in formulated water‐containing catfish mucus. Highly virulent isolate AL‐02‐36 possessed at least 2.5‐ to fivefold higher protease activity following growth in mucus than the less virulent ALG‐00‐530. Flavobacterium columnare utilized catfish mucus as a nutrient source and mucus presence modulated extracellular protease production.     

Usefulness of restriction fragment length polymorphism and spoligotyping for epidemiological studies of Mycobacterium bovis in Madagascar: description of new genotypes

Tuberculosis is highly prevalent in cattle in Madagascar. An epidemiological study based on genotyping of Mycobacterium bovis and its transmission to humans was carried out. The restriction fragment length polymorphism (IS6110 and DR markers) and spoligotyping were used to assess the genetic diversity of strains from different regions of Madagascar. One of these strains was isolated from goat, the other strains were isolated from zebu cattle. Nine IS6110 profiles, 20 DR profiles and 12 spoligotypes were obtained. About 90% of all isolates gave a single IS6110 band at about 1.8 kb. Most strains had the same spoligotype. M. bovis strains commonly lack spacers 39-43, and all Malagasy strains also lacked spacers 3-5, 8-10 and 16. This pattern has not been reported elsewhere. DR was the most discriminatory of the three markers. The patterns obtained with the three markers were combined to identify 34 different genotypes, one of which was found in 35% of the strains. No region-specific M. bovis genotype was identified, but the genotyping of 18 M. bovis strains isolated from patients showed that the human and bovine strains were identical, suggesting possible human contamination from zebu cattle.     

Stocktake study of current fertilisation recommendations across Europe and discussion towards a more harmonised approach

The European Commission has set targets for a reduction in nutrient losses by at least 50% and a reduction in fertiliser use by at least 20% by 2030 while ensuring no deterioration in soil fertility. Within the mandate of the European Joint Programme EJP Soil ‘Towards climate-smart sustainable management of agricultural soils’, the objective of this study was to assess current fertilisation practices across Europe and discuss the potential for harmonisation of fertilisation methodologies as a strategy to reduce nutrient loss and overall fertiliser use. A stocktake study of current methods of delivering fertilisation advice took place across 23 European countries. The stocktake was in the form of a questionnaire, comprising 46 questions. Information was gathered on a large range of factors, including soil analysis methods, along with soil, crop and climatic factors taken into consideration within fertilisation calculations. The questionnaire was completed by experts, who are involved in compiling fertilisation recommendations within their country. Substantial differences exist in the content, format and delivery of fertilisation guidelines across Europe. The barriers, constraints and potential benefits of a harmonised approach to fertilisation across Europe are discussed. The general consensus from all participating countries was that harmonisation of fertilisation guidelines should be increased, but it was unclear in what format this could be achieved. Shared learning in the delivery and format of fertilisation guidelines and mechanisms to adhere to environmental legislation were viewed as being beneficial. However, it would be very difficult, if not impossible, to harmonise all soil test data and fertilisation methodologies at EU level due to diverse soil types and agro-ecosystem influences. Nevertheless, increased future collaboration, especially between neighbouring countries within the same environmental zone, was seen as potentially very beneficial. This study is unique in providing current detail on fertilisation practices across European countries in a side-by-side comparison. The gathered data can provide a baseline for the development of scientifically based EU policy targets for nutrient loss and soil fertility evaluation.     

Nitrogen loading alters seagrass ecosystem structure and support of higher trophic levels

• 1. Anthropogenic‐derived nutrient inputs to coastal environments have increased dramatically worldwide in the latter half of the 20th century and are altering coastal ecosystems. We evaluated the effects of nitrogen loading on changes in macrophyte community structure and the associated fauna of a north temperate estuary. We found that a shift in primary producers from eelgrass to macroalgae in response to increased nutrient loading alters habitat physical and chemical structure and food webs. As nitrogen load increased we found increased macroalgal biomass, decreased eelgrass shoot density and biomass, decreased fish and decapod abundance and biomass, and decreased fish diversity.
• 2. The central importance of macroalgae in altering eelgrass ecosystem support of higher trophic levels is evident in the response of the ecosystem when this component was manipulated. Removal of macroalgae increased eelgrass abundance and water column and benthic boundary layer O₂ concentrations. These changes in the physical and chemical structure of the ecosystem with lower macroalgal biomass resulted in higher fish and decapod abundance and biomass.
• 3. Both a ¹⁵N tracer experiment and the growth of fishes indicated that little of the macroalgal production was immediately transferred to secondary consumers. δ¹⁵N values indicated that the most abundant fishes were not using a grazing food web based on macroalgae. Fish tended to grow better and have a greater survivorship in eelgrass compared to macroalgal habitats.
• 4. Watershed‐derived nutrient loading has caused increased macroalgal biomass and degradation and loss of eelgrass habitat, thus reducing the capacity of estuaries to support nekton.

Copyright © 2002 John Wiley & Sons, Ltd.     

Pathogenicity of West Nile virus for turkeys

In the fall of 1999, West Nile virus (WNV) was isolated during an outbreak of neurologic disease in humans, horses, and wild and zoological birds in New York, Connecticut, and New Jersey. Turkeys could potentially be a large reservoir for WNV because of the high-density turkey farming and the presence of large wild turkey populations in the eastern seaboard of the United States. Little is known about the pathogenicity of WNV in domestic or wild turkeys. Specific-pathogen-free 3-wk-old turkeys were inoculated subcutaneously with 10(3.3) mean tissue culture infective doses of a WNV strain isolated fromthe index case in a New York crow. No clinical signs were observed in the turkeys over the 21 days of the experiment. One turkey died abruptly at 8 days postinoculation (DPI). Many turkeys developed viremia between 2 and 10 DPI, but the average level of virus was very low, less than needed to efficiently infect mosquitos. Low levels of WNV were detected in feces on 4 and 7 DPI, but no virus was isolated from oropharyngeal swabs. WNV wasnot transmitted from WNV-inoculated to contact-exposed turkeys. All WNV-inoculated poults seroconverted on 7 DPI. In the turkey that died, WNV was not isolated from intestine, myocardium, brain, kidney, or cloacal and oropharyngeal swabs, but sparse viral antigen was demonstrated by immunohistochemistry in the heart and spleen. Turkeys in contact with WNV-inoculated turkeys and sham-inoculated controls lacked WNV specific antibodies,and WNV was not isolated from plasma and cloacal and oropharyngeal swabs. These data suggest that WNV lacks the potential to be a major new disease of turkeys and that turkeys will not be a significant amplifying host for infecting mosquitos.