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排序方式: 共有82条查询结果,搜索用时 15 毫秒
1.
A 5-year-old Holsteiner gelding from Germany was presented 2 months after a whitish discoloration of the left cornea was observed. Cytologic examination revealed intra- and extracellular globular structures, up to 4 micro m in size, consisting of a central spherical deeply basophilic body surrounded by an unstained halo. The structures were morphologically consistent with Histoplasma spp. Infection with Histoplasma organisms is not endemic in Europe. Topical use of fluconazole was successful in eliminating Histoplasma organisms within 10 days of initiation of treatment. 相似文献
2.
Biochemical changes in young birches in the vicinity of a highway. In spring 1975 clonal birchtrees (grafts) were exposed to polluted air at different distances from a highway. After three months’ ex-posure, leaves showed different concentrations of free amino acids, total phenols, chlorophyll a, chloro-phyll b, (3-carotene, reducing sugars and total content of vitamin C depending on distance from the highway. Also the lead concentration in moss filters showed an approximately exponential decrease with distance from the highway. 相似文献
3.
Summary In this study, the application of molecular markers to optimise genetic diversity in a polycross breeding program of perennial
ryegrass (Lolium perenne L.) was evaluated. The genetic diversity among 98 potential parental plants from three maturity groups (early, intermediate
and late flowering) was investigated using amplified fragment length polymorphism (AFLP) markers. For each maturity group,
two polycrosses of six parental plants with contrasting levels of genetic diversity were composed. Average genetic diversity
among parents selected for narrow polycrosses was 36% lower than among parents selected for wide polycrosses. Diversity within
first generation synthetic progenies (Syn1) was proportional to the diversity within the respective parental polycrosses.
However, differences were less pronounced with Syn1 progenies from narrow polycrosses showing 16% reduced diversity when compared
to Syn1 progenies from wide polycrosses. Multivariate analyses allowed for a clear separation of the six Syn1 progenies based
on AFLP markers and demonstrated their genetic distinctness. Evaluation of dry matter yield, date of ear emergence and stem
length of Syn1 and Syn2 progenies showed progenies from wide polycrosses to be constantly higher yielding when compared to
progenies from narrow polycrosses. On the other hand, there was no significant difference in variability for the two morphological
traits between progenies of narrow- and wide polycrosses. The results presented here provide evidence for an efficient application
of molecular markers to select genetically diverse polycross parents which resulted in an average yield increase of 3.8%. 相似文献
4.
Many ecosystems in Switzerland suffer from eutrophication due to increased atmospheric nitrogen (N) input. In order to get an overview of the problem, critical loads for nutrient N were mapped with a resolution of 1×1 km applying two methods recommended by the UN/ECE: the steady state mass balance method for productive forests, and the empirical method for semi-natural vegetation, such as natural forests, (sub-)alpine or species-rich grassland and raised bogs. The national forest inventory and a detailed atlas of vegetation types were used to identify the areas sensitive to N input. The total N input was calculated as the sum of NO3 ?, NH4 +, NH3, NO2 and HNO3 wet and dry deposition. Wet deposition was determined on the basis of a precipitation map and concentration measurements. Dry deposition was calculated with inferential methods including land-use specific deposition velocities. The concentration fields for NH3 and NO2 were obtained from emission inventories combined with dispersion models. Reduced N compounds account for 63% of total deposition in Switzerland. As indicated by exceeded critical loads, the highest risk for harmful effects of N deposition (decrease of ecosystem stability, species shift and losses) is expected on forests and raised bogs in the lowlands, where local emissions are intense. At high altitudes and in dry inner-alpine valleys, deposition rates are significantly lower. 相似文献
5.
Root systems of two contiguous grassland sites (fertilized meadow and abandoned grassland). In the course of an investigation on plant succession and soil development on abandoned grassland, we compared root systems in a fertilized meadow (Arrhenatheretum) with those in grassland abandoned 15 years ago (now being covered mainly by Brachypodium pinnatum). Root lengths were determined by the line intercept method developed by Newman (1966) and Evans (1970). In addition, surface areas and volumes of roots were calculated. In the top layer of the soil (0–5 cm) root lengths and root surfaces were nearly equal in the two sites, but the subsequent exponential decreases with depth were more pronounced in the meadow soil. Root volume (including rhizomes of Brachypodium pinnatum) was much larger in the abandoned grassland site. In addition, results are compared to other investigations on root density. 相似文献
6.
Mellema SC Doherr MG Wechsler B Thueer S Steiner A 《Veterinary journal (London, England : 1997)》2006,172(2):274-283
To assess short- and long-term effects of bloodless castration methods with and without local anaesthesia, behavioural and cortisol responses of lambs were used as indicators of pain and distress. Seventy lambs, aged 2-7 days, were control-handled or castrated by Burdizzo or rubber ring methods with and without local anaesthesia. Either 5 mL of diluted lidocaine (4 mg/kg) or physiological sodium chloride solution was distributed in both spermatic cords and the scrotal neck. The serum cortisol response was monitored for 48 h, and behavioural and clinical traits were followed for three months. Local anaesthesia tended to reduce behavioural and cortisol responses after Burdizzo castration and provided a significant reduction after rubber ring castration. Prolonged pain after rubber ring castration with anaesthesia was not evident. If combined with local anaesthesia, both the rubber ring and the Burdizzo methods are acceptable methods for castration of lambs up to one week of age. 相似文献
7.
Haufe HC Gygax L Wechsler B Stauffacher M Friedli K 《Preventive veterinary medicine》2012,105(1-2):85-92
In this study, the effects on the claw health of dairy cows of three different floor types and access to pasture were investigated on 35 farms. The farms were fitted with a given floor type in the indoor walking area of a cubicle housing system: a solid rubber, mastic asphalt or slatted concrete floor. Because we chose farms on which the given floor type was in good condition, the data presented show what can be achieved on these types of floors under ideal circumstances. Cows on half of the farms per floor type had access to pasture during the grazing period. Each farm was visited three times at approx. 6-month intervals at the end of the winter indoor-housing period and at the end of the summer period, i.e. after the period with access to pasture on half of the farms. During each visit, the claw health of the same 10 cows per farm was assessed on the occasion of routine claw trimming. The proportion of cows with haemorrhages increased from mastic asphalt to rubber and slatted concrete floors. A lower proportion of cows kept on mastic asphalt was affected by white-line fissures and needed intermittent claw-trimming, an indicator for lameness. Cows housed in cubicle systems with slatted concrete floors were at the lowest risk of having heel-horn erosions. Access to pasture was associated with a lower incidence of slight white-line fissures and dermatitis digitalis. A higher proportion of cows with sole haemorrhages and sole ulcers were found on all floor types at the end of the summer period than at the end of the winter indoor-housing period. Floor type did not influence the presence of sole ulcers and deep white-line fissures. In conclusion, the effect of floor type on claw health was slight, and none of the investigated floor types was clearly superior to the others. Access to pasture was not effective in reducing the presence of most types of claw lesions associated with the floor type used in the indoor walking area. 相似文献
8.
Ecotypes of Italian ryegrass from Swiss permanent grassland outperform current recommended cultivars
Beat Boller Madlaina K. I. Peter-Schmid Eliane Tresch Peter Tanner Franz Xaver Schubiger 《Euphytica》2009,170(1-2):53-65
Italian ryegrass (Lolium multiflorum Lam. ssp. italicum Volkart ex Schinz et Keller) thrives well in permanent grassland in mild and moist regions of Switzerland. Ecotypes of Italian ryegrass from Swiss permanent meadows have often been used successfully as the base material of breeding programmes. However, their agronomic performance per se has never been studied in detail. Therefore, field trials were conducted to assess the potential of this semi-natural genetic resource for use in breeding. Twenty ecotype populations were collected in different geographical regions in 2003 and seed was increased. Plot trials with 20 ecotype populations were conducted 2005–2007 at three locations, supplemented by row trials at two additional locations, and including four currently recommended cultivars as controls. Average performance in terms of yield, vigour and resistance to snow mould of ecotypes was superior to the cultivars. Depending on the characteristic, between three and 16 of the 20 ecotypes performed significantly better than the cultivars mean. However, resistance against crown rust of all ecotypes was significantly poorer than that of the cultivars. Correlation and regression analysis showed that more eastern and more northern collecting sites harboured better performing ecotypes. However, the most consistent site related factor favouring performance of the ecotypes in terms of yield, vigour, snow mould and Xanthomonas resistance was a low abundance of species which are typical of Arrhenatheretum type meadows. Data from the plot trials were related to results obtained with spaced plants at a single site, either in a seedling nursery or in the greenhouse. Resistance against crown rust was extremely well predicted by spaced plant observations. Xanthomonas resistance observed after artificial inoculation in the greenhouse was also significantly, but less closely correlated with field observations. An early date of ear emergence as observed on spaced plants was associated with high annual yield in the plot trials. It is concluded that in intensively managed habitats, natural selection has resulted in ecotype populations of Italian ryegrass which are highly promising for use in breeding. Individual plant selection for resistance can be expected to efficiently reduce their high susceptibility to crown rust. 相似文献
9.
Savary P Gygax L Jungbluth T Wechsler B Hauser R 《Berliner und Münchener tier?rztliche Wochenschrift》2011,124(1-2):17-21
In this pilot study, we tested whether a soft mat (foam covered with a heat-sealed thermoplastic) reduces alterations and injuries at the skin and the leg joints.The soft mat in the lying area of partly slatted pens was compared to a lying area consisting of either bare or slightly littered (100 g straw per pig and day) concrete flooring. In this study we focused on skin lesions on the legs of finishing pigs as indicators of impaired welfare. Pigs were kept in 19 groups of 8-10 individuals and were examined for skin lesions around the carpal and tarsal joints either at a weight of <35 kg, or at close to 100 kg. The likelihood of hairless patches and wounds at the tarsal joints was significantly lower in pens with the soft lying mat than in pens with a bare concrete floor. Pens with a littered concrete floor did not differ compared to pens with a bare concrete floor. The soft lying mat thus improved floor quality in the lying area in terms of preventing skin lesions compared to bare and slightly littered concrete flooring. Such soft lying mats have thus the potential to improve lying comfort and welfare of finishing pigs. 相似文献
10.
European natural and semi-natural grassland form reservoirs of genetic resources containing highly adapted and variable ecotype
populations of forage plants. Variation within these reservoirs is stimulated by variation in natural and anthropogenic site-related
factors. Changes in agricultural practices lead to the loss of many characteristic habitats. In order to preserve resources
for breeding, targeted conservation strategies for germplasm in gene banks (ex-situ) or on site (in-situ) are needed. In order
to define site-related criteria for the potential of habitats to preserve valuable resources for breeding and conservation,
38 different habitats across Switzerland were selected to collect Festuca pratensis Huds. and Lolium multiflorum Lam. ecotype populations. Phenotypic variation and population differentiation of 60 single plants were evaluated in a field
experiment using 16 morpho-physiological traits. For F. pratensis, ecotype populations and cultivars were clearly separated and there was a significant correlation between diversity of morphological
traits and geographic location of sampling sites. For L.
multiflorum no clear separation of ecotype populations and cultivars was observed suggesting gene flow from adjacent temporary leys into
permanent grassland. Several ecotype populations were superior to cultivars in important traits such as early heading or resistance
to winter damage, indicating the importance of natural habitats as a reservoir of genetic resources for breeding. In conclusion,
maintenance of permanent grassland in contrasting environments appears to be a promising strategy for preserving valuable
genetic variation of forage grasses.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献