Implications of Uncertainty in a Pre-treatment Dataset when Estimating Treatment Effects in Paired Catchment Studies: Phosphorus Loads from Forest Clear-cuts

Water, Air, & Soil Pollution - Estimates of increased nutrient export caused by forest clear-cuttings are mostly based on long-term paired catchment studies, where the treatment effect is...     

Rainbow trout (Oncorhynchus mykiss) immune response towards a recombinant vaccine targeting the parasitic ciliate Ichthyophthirius multifiliis

The protective effect in rainbow trout (Oncorhynchus mykiss) of an experimental subunit vaccine targeting antigens in the parasite Ichthyophthirius multifiliis has been evaluated and compared to effects elicited by a classical parasite homogenate vaccine. Three recombinant parasite proteins (two produced in E. coli and one in insect cells) were combined and injected i.p., and subsequently, protection and antibody responses were analysed. Both the experimental and the benchmark vaccine induced partial but significant protection against I. multifiliis when compared to control fish. Specific antibody responses of vaccinated trout (subunit vaccine) were raised against one neurohypophysial n‐terminal domain protein #10 of three recombinant proteins, whereas the benchmark vaccine group showed specific antibody production against all three recombinant proteins. The immunogenic parasite protein #10 may be a potential vaccine candidate supplementing the protective I‐antigen in future vaccine trials.     

More or less moose: how is the hunting value affected?

In Sweden, management of moose is important due to considerable values as well as costs associated with this game species. An overarching question is how much moose Sweden should have. This short communication is delimited to the question of what the hunting value of moose is and what the hunting value would be given alternative levels of moose population density and allowed harvest. It is based on data from a mail contingent valuation survey that involved randomly selected hunters from a national register. The results showed that moose was the economically most important game species in Swedish hunting. The results also suggested that the hunting value would increase, but at a decreasing rate, if the moose population density and allowed harvest were increased – and vice versa. The findings should be of considerable interest in the context of adaptive moose management.     

Phosphorus and nitrogen turnover and risk of waterborne phosphorus emissions in crop rotations on a clay soil in southwest Sweden

Abstract. Nutrient losses from arable land are important contributors to eutrophication of surface waters, and phosphorus (P) and nitrogen (N) usually act together to regulate production of Cyanobacteria. Concentrations and losses of both nutrients in drainage water from pipe drains were studied and compared in 15 crop rotations on a clay soil in southwest Sweden. Special emphasis was placed on P and it was possible to evaluate critical components of the crop rotations by flow-proportional water sampling. Total P concentrations in drainage water were generally small (0.04–0.18 mg L⁻¹), but during two wetter years out of six, high P concentrations were measured following certain management practices, including ploughing-in lucerne ( Medicago sativa L.) and fertilizing in advance without incorporation into the soil to meet the needs of several subsequent crops. This resulted in average flow-weighted concentrations of total P between 0.3 and 0.7 mg L⁻¹. In crop rotations containing green manures, green fallow or leguminous leys, there was also a risk for increased P losses after these crops were ploughed in. The losses increased in the order: cash crops < dairy with grass < dairy with lucerne < monoculture with barley < organic farming with cattle slurry < stockless organic farming with green manure. P balances varied between −9 and +8 kg P ha⁻¹ and N balances between +4 and +35 kg N ha⁻¹. The balances were not related to actual leaching losses. Phosphorus losses in drainage from set-aside were 67–82% of those from cash crops grown in ploughed and P-fertilized soil at the same site, indicating a high background P loss from this clay soil.     

Pine weevil (Hylobius abietis) damage to cuttings and seedlings of Norway spruce

Damage caused by pine weevil (Hylobius abietus L.) to planted seedlings and cuttings of Norway spruce (Picea abies (L.) Karst.) was studied at five clearcut sites in south-eastern Sweden. The main objective was to compare the two types of stock in terms of attack frequency and mortality due to pine weevil feeding. Cuttings and seedlings with the same initial stem-base diameter (4 mm) were compared. Two sites were harvested and scarified shortly before planting, two were harvested shortly before planting, but were not scarified, and one was harvested 2 years before and scarified the autumn before planting. The total mortality 5 years after planting was highest, greater than 90%, at the new, non-scarified sites, and lowest, 23%, at the old, scarified site. More than 90% of the mortality was caused by pine weevil feeding. Attack frequency and pine weevil induced mortality were significantly higher among seedlings than among cuttings. Mortality due to pine weevil damage was 4–43% higher in seedlings than in cuttings after the fifth year. Of the cuttings and seedlings that were attacked in the first year, a significantly higher frequency of the seedlings were girdled. The higher resistance of cuttings to pine weevil damage may partly explain the more rapid growth of cuttings reported in other studies. However, the causes of their higher resistance need to be further investigated. The thicker bark and needles on the stem base of the cuttings could be important in this respect.     

Response of soil exchangeable and crop potassium concentrations to variable fertilizer and cropping regimes in long-term field experiments on different soil types

Annual potassium (K) balances have been calculated over a 40‐year period for five field experiments located on varying parent materials (from loamy sand to clay) in south and central Sweden. Each experiment consisted of a number of K fertilizer regimes and was divided into two crop rotations, mixed arable/livestock (I) and arable only (II). Annual calculations were based on data for K inputs through manure and fertilizer, and outputs in crop removal. Plots receiving no K fertilizer showed negative K balances which ranged from 30 to 65 kg ha^?1 year^?1 in rotation I, compared with 10–26 kg ha^?1 year^?1 for rotation II. On sandy loam and clay soils, the K yield of nil K plots (rotation I) increased significantly with time during the experimental period indicating increasing release of K from soil minerals, uptake from deeper soil horizons and/or depletion of exchangeable soil K (K_ex). Significant depletion of K_ex in the topsoil was only found in the loamy sand indicating a K supply from internal sources in the sandy loam and clay soils. On silty clay and clay soils, a grass/clover ley K concentration of ～2% (dry weight) was maintained during the 40‐year study period on the nil K plots, but on the sandy loam, loam and loamy sand, herbage concentrations were generally less than 2% K.     

An interlaboratory comparison of immunohistochemistry and PCR methods for detection of Neospora caninum in bovine foetal tissues

Seven European laboratories contributed to a multi-centre evaluation of detection techniques for Neospora caninum in bovine foetuses. Six laboratories participated in immunohistochemistry (IHC) testing. All seven laboratories participated in PCR testing, but the results from one laboratory were not included in the analysis, because of contamination problems in the preparation of the samples. A coded panel of tissue sections from 36 infected and non-infected foetuses was used to evaluate the IHC detection of parasites. A coded panel consisting of 44 homogenized foetal brain samples from natural bovine abortion cases and 32 spiked samples were used to evaluate the PCR methods. Inclusion of a duplicate dilution series of spiked samples was used to evaluate detection limits and repeatability. IHC methods had a relatively low sensitivity, but a high specificity. There was considerable variation in IHC results between participating laboratories, which may be partly explained by examination practices that depended on the experience of the operator. In addition, the use of different antibody reagents, different antibody dilutions, and different enzymatic treatments of tissues may have contributed to the observed variation. PCR methods generally had a higher sensitivity than IHC methods and also a high specificity. The agreement between the majority scores of IHC and PCR methods was low. False positive PCR results indicated contamination problems in some instances. Agreement between the PCR results of the various laboratories was better, compared with the IHC results. There appeared to be no clear relationship between the PCR format (i.e. single or nested) and diagnostic sensitivity. Consequently, an improvement of diagnostic performance of PCR might possibly be achieved by optimizing DNA extraction methods.     

Development of post-weaning diarrhoea in piglets. Relation to presence of Escherichia coli strains and rotavirus

Weaning of piglets complicated with an exposure to pathogenic strains of Escherichia coli was scrutinized in two sets. The first set comprised 20 animals representing two litters and the second set included 30 animals from five litters. The piglets were either left as controls or exposed to one or three pathogenic strains of E. coli. Aiming to simulate a natural exposure the challenge strains were spread on the floor of the pens at weaning. In addition the pigs experienced several non-infectious stress factors commonly occurring at that occasion. Some groups were given adrenocorticotropic hormone (ACTH), aiming to simulate a stressful weaning. The balance and the composition of the faecal coliform populations, measured by a metabolic fingerprinting method, was disturbed among all animals following weaning. This disturbance was more pronounced and lasted longer among piglets exposed to pathogenic strains of E. coli. All piglets exposed to pathogenic E. coli shed these strains in faeces. Diarrhoea was induced in the groups exposed to E. coli, but not among the control animals. Pigs not treated with ACTH and subjected to a single pathogenic strain of E. coli became infected but did not develop diarrhoea unless if coinciding with shed of rotavirus. Control pigs excreting rotavirus had no diarrhoea. Diarrhoea was most frequent in the groups exposed to three pathogenic strains of E. coli, and in these groups diarrhoea was seen in the absence of rotavirus. ACTH administration amplified the clinical signs. The litter of origin influenced the development of post-weaning diarrhoea.     

Mycotic proventriculitis in gray partridges (Perdix perdix) on two game bird farms

Proventriculitis and chronic respiratory disease were diagnosed in two flocks of gray partridges (Perdix perdix) on unrelated Swedish game bird farms. Affected birds showed loss of condition, respiratory signs, and flock mortality rates of 50 and 98%, respectively. The proventricular lesions were associated closely with fungal organisms that were microscopically indistinguishable from the ascomycetous yeast Macrorhabdus ornithogaster (former provisional name "megabacterium"). At necropsy, the proventriculi were swollen and hyperemic, and viscous mucus adhered to the mucosa. Proventricular hemorrhages were commonly detected, and one bird had proventricular rupture and peritonitis. Microscopically, mild to severe subacute to chronic lymphoplasmacytic proventriculitis, microabscesses, necrosis, epithelial metaplasia, disrupted koilin, ulcers, and hemorrhages were observed. Transmission electron microscopy of the proventricular microorganisms revealed a membrane-bound nucleus, vacuoles, ribosomes, microtubules in parallel arrays, and a two-layered cell wall but no mitochondria. Scanning electron microscopy of the proventricular epithelium demonstrated masses of organisms with occasional constrictions in parallel arrangement. Many of the birds also suffered from concurrent respiratory bacterial infections and/or gastrointestinal candidiasis. The clinical course and gross and microscopic proventricular lesions were similar to those described in psittacine and passerine pet birds colonized by M. ornithogaster-like microorganisms but differed from published case reports and experimental infections of chickens in which the clinical signs and lesions have been considerably milder. The findings presented in this paper suggest that mycotic proventriculitis, presumably associated with M. ornithogaster, may be a serious but possibly opportunistic, although unusual, disease problem in gray partridges on game farms.     

Prevalence of antibodies against Toxoplasma gondii and Neospora caninum in Hungarian red foxes (Vulpes vulpes)

In the present study we have investigated the seroprevalence to the protozoan parasites Toxoplasma gondii and Neospora caninum in 337 red foxes (Vulpes vulpes) from 16 out of 19 counties in Hungary. The foxes were originally collected within a National vaccination program against rabies. Antibodies to T. gondii were detected in as many as 228 (68%) of the foxes using a commercial direct agglutination test (DAT). In an indirect iscom ELISA, five foxes (1.5%) were positive for antibodies against N. caninum. The high prevalence of foxes positive for T. gondii might be explained by the widespread occurrence of the parasite in the diet of foxes. As a contrast, latent infections of N. caninum among red foxes in Hungary are much less common.